■ 






1 1 1 








■ ■ 



■ 



■ 



■ 









■ I 



I ■ 



■ 









w<\/ 



5> *L'*Lr* '■> 



•^A ^ <? 



c5 °\> '-• ^^Sm^^ o A^^ 







'^'* > 



I • %<- A** * (COCSR A °„ "& ,£* ♦ fSii2S r> A V * cCCvW A° ^V. «£ 









v^ v 



"o^ 













0^ .•^L-..*o 



V 









> "*, 3 






o <>. _<A ♦«iak. ^ A? .A¥A» <>. .C$ *• 



***<? 



%<? :>. 



" «V Civ 



^ S \ : .S1K: ** v ^. 






y *«• %* 







,«• 



f /\ : --»* y% "••^• ; / 






^ 


























* J -o< 



V *oTo» ^ o *.,,. .o V * e „ o a- o ».,,. .o <v •...• .^ o «-.,,.* 






**<? 



• ♦ 4- v * 












^^' 



v\^% 



<? \J$Ws^ %'^<J' X*fQf\S %'-o.^-^ ^-•TKT.-A 




<« .*«?^ia"- ^«^ .-'^^•- "'^ <" •^iS'- «b>* :jfii^*- ^o« :^ia: ^v* 







• «5 °^ 




jP^v 




.• ^°- 














IT*' A 

A* • l " * ^ 




• -^ ^ .>V/k*-. >. .«r * v ?sfe'. «c ^ .^Va\ >. .c^ •*. 









<• AV * 






.• «r^ v^s^-'. ^"-^ 




^6* 



o > 




&■ " o » o •$ 










^«0« 



' ,* 6 .-..V' •".4^. .,..%/"">♦' 

/ o ;.^^ o V^*V V*^*^ V^'V 



* 








;. '^o< ? 







^ e.4* ! ^ ^ a5< ' /, 



w 



^«^ 

"/''? 






■P V 













••' 4 -^ 















« *t 







?^ 








^" A* V "V 

113* aV ^ 



rr* a 



v* 














^ *?^T* A 












"of 
> - » "^>_ "J 



\W\/ ^:W'/ \$@y \W\o-> v»-'/ v^; 






* AT ^ 



» » " A 1 *' ^ *••«* A ^» 



* .*y ^ 



o, *v7.«* .A 






7X* A 



ct •« 






'» ^ 

^ 



^ .o«o. *« A N .t..« *W .o* ...... * . A^ ..' 



o» o. - 



:. "^ri«" =<^^^"» ^ov v 






•,• ^V '^ 



^°% 



r. ^ < f. 



,<* y, 



"of 










j? »i 



i" A^ V< V 















°^^ 







'♦ ^ 



:. %. .^ SiStok. «, a* /Avl*,^ .,4 V .*as% ^ a* v /AVa\^. ^- .*»*. ■«. a* 



■ 









£°1* 



,0. 



— 












'• A V "^ 

V ** % 



V -WIT ^ °^ 



^ .IV * jA>5(T A, <• '■<*• (A » 



^.c^ 



U j»$^ 



A <\. *?.?• G* 





<w 









»iV£\ "*. c° 






*++# 
^ 



A <* *o.7" ,G V 

* > • l ' • . ** o^ , ° " • . 



«bv* 

» ^ 



:. -w •' 



£9* 






/ V X •-!»•• y% W? ; /\ -SgK-- ^ v \ : .?R?.- 







V -a* v 







°o. '^^^ 



»°v 




V 



^ 










o 41 






.* ft9 



»p-nK ' 

















it 1 
















• V** * 



.4* s~j»*L-> %. c° 



fe\ v.** -jfcV/fr. v>* yeafe--. ** *♦ .^Va--. ^ ^ ^^k-. 




>* _ o » » . < 



uc*- *'/32^>» '^^ 








G°* 






V ^ ^ <* 











* o 



. .5 ,> 






6*% 



& ...... ^ 



*bV" 



>°^, 



v^>°\.. ^^^-,/ %*^^%o° -^ 




<^ *.... G 

G° 



.* ^ u-m&s a 



* a" o 






*« <^ 



^ ^ 












A^ ^. " 










"b * 

■* ^ v ^>°:« % a*° *^l*. # * 







'"^d 5 
.^^ 




*bv* 



q.* r A0' J V^TtTo* y 

v 







< ^.q-? .», 













. A.h » ft 

5> v *' VL'. *> 



Jo 
• if * 







%. *•.'•' A 

^ A* 



^A * 




A^°*. 







'^ A^ 






°' ^ A* 3 

■^a A* 









0. *;"",•' .0 



A0\,r^% *> 



>.. "o.o' O 



,y%'~'''j? %.' , ^-'\<>' \'-^-\<>^ V'^^'V \"wt>'' ^ *%•'?$>'' 



IC 


9040 



Bureau of Mines Information Circular/1985 



Environmental Issues Related to Mineral 
Development in the Stillwater Complex, 
MT 

By Michael T. Nigbor, Stephen R. Iverson, and Paul C. Hyndman 




UNITED STATES DEPARTMENT OF THE INTERIOR 



75! 

Mines 75th a^ 



(AJ^UMtJjs. | W^ ^ 



Information Circular 9040 



Environmental Issues Related to Mineral 
Development in the Stillwater Complex, 
MT 

By Michael T. Nigbor, Stephen R. Iverson, and Paul C. Hyndman 




UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Hodel, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 



°F degree Fahrenheit 

ft foot 

ft 3 cubic foot 

ft^/yr square foot per year 

g/h gram per hour 

gpm/ft 2 gallon per minute 



min 

ml* 

urn 

mph 

MW 

NTU 





per square foot 


h 


hour 


in 


inch 


in/yr 


inch per year 


kW 


kilowatt 


lb 


pound 



minute 

milliliter 

micrometer 

mile per hour 

megawatt 

nephelometric 
turbidity unit 



lb/acre pound per acre 



ug/m 3 



microgram per cubic meter 



pet percent 

ppm part per million 

tpd ton (short) per day 

tpy ton (short) per year 

wt pet weight percent 

yd 3 cubic yard 

yr year 



Library of Congress Cataloging in Publication Data: 



Nigbor, Michael T 

Environmental issues related to mineral development in the Still- 
water Complex, MT. 

(Information circular ; 9040) 

Bibliography: p. 32-33. 

Supt. of Docs, no.: I 28.27: 9040. 

1, Mineral industries— Environmental aspects— Montana. I. Iverson, 
Stephen R. II. Hyndman, Paul C. III. United States. Bureau of Mines. 
IV. Title. V. Title: Stillwater Complex, Montana. VI. Series: Infor- 
mation circular (United States. Bureau of Mines) ; 9040. 

TN295.U4 [TD195.M5] 622s [338.2'74] 85-600062 







f\0< 






PREFACE 

This report provides information on the environmental issues associ- 
ated with mining strategic minerals in the Stillwater Complex, MT. It 
is not an environmental impact statement and is not meant to serve as 
one. Its purpose is informational; it is intended for use by planners 
in the minerals field. If any of the potential operations discussed in 
this report should become reality, separate, site-specific environmen- 
tal impact statements will be required. 

In general, the scenarios used to estimate production ranges were 
constructed with the goal of domestic mineral self-sufficiency in mind. 
Beyond this, political and policy issues associated with such mining 
operations were not considered. 

The reader is reminded that the mining operations described are based 
on hypothetical scenarios. At the time this report was prepared, only 
the 1,000- tpd platinum-group metal (PGM) operation had any firm plans 
associated with it. The authors are aware of no plans to produce Cr or 
Ni from deposits in the Stillwater Complex. 



Ill 



CONTENTS 

Page 

Abstract. 1 

Introduction 2 

General description of the Stillwater Complex 2 

Regulatory environment 3 

Operation descriptions 6 

Chromium 6 

PGM 7 

Nickel-copper 9 

Land issues 12 

Tailings disposal plans 12 

Chromite tailings 12 

PGM tailings — Minneapolis Adit site 12 

PGM tailings — Hertzler Ranch site. 13 

Nickel-copper tailings 14 

Combined tailings 14 

Tailings pond reclamation 14 

Chromite tailings 14 

PGM tailings 15 

Nickel-copper tailings 15 

Ferrochrome smelter waste 15 

Waste rock 17 

Land use changes 17 

Visual impacts 18 

Summary of land issues 18 

Water issues 21 

Surface waters baseline quality 21 

Mine drainage water quality 23 

New source performance standards 24 

Ferrochrome smelter waste water 24 

Nickel-copper processing waste water 26 

Diversion of streams 26 

Summary of water issues 27 

Air issues 27 

Baseline air quality 27 

Ferrochrome smelter gas emissions 28 

Dust 30 

Other air issues 30 

Other issues 31 

Noise 31 

Power, transportation, and housing 31 

Conclusions 31 

References 32 

ILLUSTRATIONS 

1. General geology of study area, showing the Stillwater Complex 3 

2. Looking west across the Stillwater River at the Mouat chromite and Ni-Cu 

areas 4 

3 . Geologic map of the Mouat Mine area 5 

4 . Plan map of Cr mine-mill-smelter facilities 6 

5 . Plan map of PGM mine-mill facilities .• 7 



ILLUSTRATIONS — Continued 



Page 



6. Minneapolis Adit, main haulage for PGM operations..... 8 

7. Plan map of tailings pond at Hertzler Ranch area for PGM operations, high 

production rate 9 

8. Hertzler Ranch area. 10 

9. Plan map of combined operations, a hypothetical worst case 10 

10. Verdigras Creek 11 

11. Upstream and centerline methods of constructing tailings dams 13 

12. Waste rock terracing method 17 

13. Visual effects of PGM mining operations at the low production rate 19 

14. Visual effects of combined operations, a hypothetical worst case 19 

15. Visual effects of Ni-Cu open pit from Beartooth Ranch 20 

16. Visual effects of Ni-Cu open pit from Woodbine Falls 20 

17. Water sample locations 21 

18. Ferrochrome smelter water treatment system 26 

19. Wind roses from the Stillwater River Valley.' 28 

20. Ferrochrome smelter air control system 29 

TABLES 

1. Revegetation species used in reclamation 14 

2. Water quality regulatory standards 22 

3. Surface water samples exceeding regulatory standards 22 

4. New source performance standards for Ni mining and milling 24 

5. New source performance standards for Pt mining and milling 24 



ENVIRONMENTAL ISSUES RELATED TO MINERAL DEVELOPMENT 
IN THE STILLWATER COMPLEX, MT 

By Michael T. Nigbor, Stephen R. Iverson, and Paul C. Hyndman 



ABSTRACT 

This Bureau of Mines publication identifies the significant environ- 
mental issues associated with the potential development of strategic 
and critical minerals in the Stillwater Complex, MT. The Stillwater 
Complex contains deposits of Cr, platinum-group metals (PGM), and Ni. 
Issues that must be addressed prior to minerals development include the 
effects mining, milling, and smelting will have on the land, water, and 
air, and methods of minimizing the environmental impacts. 



^Mining engineer, Denver Research Center, Bureau of Mines, Denver, CO. 

^Mining engineer, Western Field Operations Center, Bureau of Mines, Spokane, WA. 



INTRODUCTION 



Our Nation depends on foreign sources 
for a host of mineral products. One of 
the Bureau's main goals is to minimize 
such dependence, by conducting research 
that leads to technology for better uti- 
lizing domestic resources. The Bureau 
also maintains current statistics on 
import dependence, production, and 
recycling (J_) . 3 

The strategic and critical minerals is- 
sue has been described in the literature. 
A recent publication, "World Index of 
Strategic Minerals: Production, Exploi- 
tation, and Risk" (2^, provides a very 
complete summary of the issue. 

A potential domestic source of some 
strategic minerals is the Stillwater Com- 
plex, in south-central Montana. It is a 
geologic structure that contains deposits 
of Cr, PGM, and Ni. The Nation's largest 
known resources of Cr and PGM are located 
here (3). Nickel deposits are smaller, 
but still significant. The PGM deposits 
are possibly economic to mine, and in 
fact are being evaluated by the Stillwa- 
ter Mining Co. for economic viability. 
The Cr and Ni deposits are not considered 
economic to mine at today's prices. 

Certain environmental issues could af- 
fect the development of domestic strate- 
gic and critical deposits such as those 
in the Stillwater Complex. Environmental 



regulations resulting from the National 
Environmental Policy Act, the Clean Water 
Act, the Clean Air Act, and others set 
standards for the development of mineral 
deposits by requiring the consideration 
of environmental impacts and the limita- 
tion of certain types of waste discharges 
(4). This report attempts to identify 
the major environmental issues in the 
Stillwater Complex, to describe baseline 
conditions, and to suggest solutions to 
environmental problems related to poten- 
tial strategic mineral development. With 
this information and with adequate plan- 
ning, development can occur in a timely 
fashion without undue environmental 
impacts. 

In determining environmental issues, 
the strategy taken was to assume two sce- 
narios for each commodity, one low-end 
scenario and one high-end scenario. The 
low- and high-end scenarios were estab- 
lished by analysis of minimum economic 
size, most likely mining method, size of 
resource, current technological limita- 
tions, and current market consumption. 
The low- and high-end scenarios can be 
thought of as resulting in minimum and 
maximum potential environmental effects, 
respectively. In this way, the most 
likely production rates were bounded by 
the low- and high-end scenarios. 



GENERAL DESCRIPTION OF THE STILLWATER COMPLEX 



The Stillwater Complex is a magraatic 
segregation geologic structure 1 to 5 
miles wide and 28 miles long. It is 
located about 60 miles southwest of Bil- 
lings, MT (fig. 1). The complex occurs 
in the Beartooth Mountains of the Rocky 
Mountain physiographic province. The 
complex is oriented in a northwest- 
southeast direction. 

The complex is cut on the southeast 
third by the Stillwater River Valley, 
a broad, glaciated, northeast-trending 
valley (fig. 2). Elevation at the valley 
floor is about 5,000 ft above sea level. 

■^Underlined numbers in parentheses re- 
fer to items in the list of references at 
the end of this report. 



Chrome Mountain, in the northwest third, 
is the highest point in the complex, 
about 10,000 ft above sea level. 

The West Fork Stillwater River cuts the 
complex about 5 miles northwest of the 
Stillwater River. The West Fork Stillwa- 
ter River runs in a narrow canyon, the 
floor of which is about 6,500 ft above 
sea level at the complex. The East Boul- 
der River cuts the complex 5 miles far- 
ther along in a similar steep canyon. 
The Boulder River Valley forms the ter- 
minus of the complex on the northwest. 
The Boulder River has an elevation of 
about 5,000 ft above sea level at the 
complex and runs essentially south-north. 
Northeast of the Stillwater Complex, the 
Boulder and Stillwater Rivers flow into 




© 



LEGEND 
Sedimentary rocks 
Stillwater Complex 
Metamorphic rocks 
Mines (inactive) 
) Gish (Cr) 
Mouat (Cr) 
Mouat (Ni-Cu) 
Stillwater (PGM) 
Benbow (Cr) 



\ MON 






MONTANA 

Study a 



FIGURE 1. - General geology of study area, 
showing the Stillwater Complex. 

the Yellowstone River, which in turn 
flows to the Missouri River. 

Northeast of the complex, the topog- 
raphy changes from mountainous to more 
gentle terrain. Mesas and hogbacks sep- 
arated by broad valleys give way to 



rolling topography. South and west of 
the complex, the topography again becomes 
mountainous in the Beartooth Range, 
with some peaks exceeding 14,000 ft in 
elevation. 

Mining activity in the Stillwater Com- 
plex includes past mining of chromite (5- 
6_) , current development of PGM, and ex- 
ploration for Ni and Cu. 

The Stillwater Complex is a layered 
magma intrusive, consisting of three ma- 
jor units: the Basal, Ultramafic, and 
Banded zones. Nickel, copper, chromium, 
and PGM occur in high concentrations in 
specific zones of the complex. In the 
Basal zone, Ni occurs as pentlandite in 
pyrrhotite and Cu occurs as chalcopyrite. 
Chromium occurs as chromite in the Ultra- 
mafic zone, and the PGM occur as several 
platinum-group sulfides in the Banded 
zone. The Ni-Cu sulfides are generally 
in discontinuous irregular layers. The 
chromite occurs in several lenses and 
layers, alphabetically designated, with 
two layers, the G and H zones, being 
the thickest and most continuous. The 
platinum-group sulfides occur in an al- 
most continuous zone 3 to 6 ft thick. 

The geology of the Stillwater Complex 
has been discussed in the literature (7- 
8). Geologic maps of the Stillwater Com- 
plex area and the Mouat Mine area are 
shown as figures 1 and 3. 



REGULATORY ENVIRONMENT 



The regulatory environment (the envi- 
ronmental and mine development regula- 
tions and agencies) is complex; however, 
a brief description is presented here. 

The National Environmental Policy Act 
(NEPA) of 1969 directs all Federal agen- 
cies to provide environmental impact 
statements (EIS's) to the U.S. Council on 
Environmental Quality before proceeding 
with any major action that significantly 
affects the environment. NEPA' s require- 
ments are supplemented by the Montana 
Environmental Policy Act (MEPA) . MEPA's 
more stringent requirements would super- 
sede those of NEPA. MEPA and NEPA re- 
quirements extend to both State and Fed- 
eral lands within Montana. 

In the Stillwater Complex, mining oper- 
ations can potentially be on U.S. Forest 



Service (USFS) land and private lands. 
Montana Department of State Lands (DSL) 
administers the 1971 Montana Metal Mine 
Reclamation Act (formerly the Hard Rock 
Mining Act) , which applies to all lands 
within Montana. DSL has sole regulatory 
authority on patented mining claims with- 
in Federal lands. DSL requires that a 
reclamation plan be submitted and ap- 
proved as part of an application for an 
operating permit. A bond would also be 
posted to ensure that adequate funds are 
reserved for future land reclamation (9) . 
DSL would regulate mining activity on 
both Federal and private lands. 

USFS regulates mining activity under a 
number of laws, including the 1872 Mining 
Law and amendments, the Organic Admini- 
stration Act of 1897, the Mining and 




FIGURE 2. - Looking west across the Stillwater River at the Mouat chromite and Ni-Cu areas. 



Mineral Policy Act of 1970, the National 
Materials and Minerals Policy, Research, 
and Development Act of 1980, and a number 
of Executive (Presidential) Orders. USFS 
manages surface resources on unpatented 
mining claims and issues permits for op- 
erations primarily limited to facilities 
and uses of forest lands. 

A proposed PGM operation at the Min- 
neapolis Adit would be an example of 
a combined Federal-State jurisdiction. 
Most of the proposed mine is in a na- 
tional forest, while the associated sur- 
face facilities are on private land. 
Before the company can commercially de- 
velop its mineral properties, it requires 
an operating permit from DSL, an approval 



of its plan of operations from USFS, and 
air and water quality permits from the 
Montana Department of Health and Environ- 
mental Sciences (MDH&ES) . An EIS must 
be prepared in accordance with MEPA and 
NEPA requirements to be used as a guide 
for approval of permits and operation 
plans. A draft EIS on the project ( 10 ) 
was filed jointly by DSL and USFS in 
1985. 

An EIS must contain data on base- 
line conditions, the proposed operation, 
alternatives to the proposed operation, 
and its environmental impacts. Most of 
this information would be provided in 
the application(s) for a raining permit 
filed by the developer with DSL, USFS, 




Scale, ft 



Q Quaternary alluvium 



LEGEND 

t ■ ■ ■ ■ ■ i Archean hornfels regionally 
*■ ' ■ > r ^' metamorphosed 



[;■;;; Pji;'.;^ Paleozoic sedimentary rocks * Mines 

® Mouat (Cr) 
© Mouat (Ni-Cu) 



Aqmg Archean quartz monzonite 



i * ■ »] Archean banded zone 

IV*. .1 (platinum group within this zone) © Stillwater (PGM) 

y/AJS/A Archean ultramafic zone * — » — » Thrust fault 

V/iii/A (chromite bands within this zone) 

I i ' ■ ! ' A t>J 1 1 1 1 Archean basal zone 



(Ni-Cu sulfides) 



FIGURE 3. - Geologic map of the Mouat Mine area. 



or both. The result is that the devel- 
oper bears the expense of generating the 
data for the EIS that is required before 
an agency can grant a mining permit. 

Beyond the requirements for a mining 
permit and an EIS, each operation in the 
Stillwater Complex would also need per- 
mits to discharge waste into the air and 
water. These requirements are estab- 
lished in the Clean Air Act and the Clean 
Water Act and are administered by the En- 
vironmental Protection Agency (EPA) or 
the State if it has approved programs. 

EPA has promulgated regulations limit- 
ing the types and amounts of various 
pollutants allowed from mining, mill- 
ing, and smelting operations. In par- 
ticular, regulations called new source 
performance standards (NSPS) for mining, 
milling, and smelting have recently been 



issued (11). These regulations would 
have an impact on any potential mineral 
operations in the Stillwater Complex. 

The Montana Department of Natural Re- 
sources and Conservation (DNR&C) admini- 
sters air and water pollution regulations 
under State law. In accordance with an 
agreement between the EPA and DNR&C, 
DNR&C administers EPA's air and water 
programs within the State of Montana, 
thereby streamlining the permit process. 
The agreement basically states that Mon- 
tana's program has been reviewed by the 
EPA and approved as being at least as 
rigorous as the national program. 

Other requirements before a mineral 
operation can go into production in- 
clude permits required by the U.S. Mine 
Safety and Health Administration, the 
U.S. Occupational Safety and Health 



Administration, and various local author- 
ities. Most of these permits are related 
to the health and well-being of workers 
and not directly to environmental issues. 



The Montana Hardrock Mining Impact Board 
requires that a company supply prepay- 
ment for estimated socioeconomic impacts 
due to planned mining operations. 



OPERATION DESCRIPTIONS 



Two scenarios were selected for Cr op- 
erations: the low-end scenario was based 
on a production rate of 1,000 tpd ore and 
the high-end scenario used 2,500 tpd ore. 
Operations outside this range were con- 
sidered unlikely, based on engineering 
considerations, the nature of demand for 
Cr , and the extent of the resources. 

Two scenarios were selected for PGM op- 
erations , based on recent development 
in the area and demand for PGM. The low- 
end scenario used a production rate of 
1,000 tpd, and the high-end scenario used 
4,000 tpd. 

Only one scenario was used for Ni-Cu 
operations. The production rate selected 
was 27,500 tpd ore, with 24,800 tpd 
waste. This size is speculative, as 
very few solid engineering data were 
available. 

The following three sections provide 
basic information on potential Cr , PGM, 
and Ni-Cu mining and milling operations 
in the Stillwater Complex. 

CHROMIUM 

Two scenarios were examined for a mine- 
mill-furnace, chromite-to-f errochrome fa- 
cility. The low-end scenario included a 
1,400-tpd mine, 1,000-tpd mill, and 750- 
tpd furnace to produce 230 tpd of high- 
carbon f errochrome. The high-end scenar- 
io included a 3,500-tpd mine, 2,500-tpd 
mill, and 1,800-tpd furnace to produce 
545 tpd of high-carbon ferrochrome. Op- 
erational lives for the two scenarios 
would be 35 and 14 yr , respectively. For 
both scenarios, the mine will operate 
5 days per week and the mill will operate 
7 days per week. Total speculative re- 
sources in the G and H zones are 13 mil- 
lion tons of chromite averaging 21 pet 
Cr 2 3 . Figure 4 shows the potential lo- 
cation of the facilities. 

The mine would consist of a 12,000- 
ft main haulage adit, a 1,600-ft under- 
ground shaft, and underground facilities 
to service the workers and equipment 



during shrinkage stope mining of the two 
chromite ore zones. The 4,000-ft Monte 
Alto Adit would be rehabilitated and 
extended about 7,800 ft to intersect the 
G and H zones at an elevation of 5,470 
ft. A rapid-tunneling machine could be 
used to drive the 10- by 10-ft adit. 

The 12-ft-diam service shaft collar 
would be located about 700 ft west of the 
face of the H zone on the No. 5 
of the old Mouat Mine. The lowest 
of the shaft, the 5470, would be 
200 ft north of the main haulage 



level 

level 

about 

adit 



and about 9,800 ft from the Monte Alto 




LEGEND 

1 Monte Alto Adit 

2 Coarse ore stockpile and crusher 

3 Fine ore stockpile 

4 Mill and enqueuing building 

5 Dry and shop 

6 Bnquetted mill concentrate stockpile 

7 Smelter leed stockpiles, coal char, 
limestone, and quartz 

8 Ferrochrome smelter area 

9 Sag storage a 
TO Sludge storage area 
1 1 Ferrochrome stockpile 

12 Office buildings 

13 Tailings storage area 
M Site of old tailings area. 1943 
15 Site of old tailings area. 1953-61 



FIGURE 4. - Plan map of Cr mine-mill-smelter 
facilities. 



portal. The shaft would have nine sta- 
tions above the main haulage about 180 ft 
apart. 

Ore would be mined using the shrink- 
age stope methods utilized previously at 
the Mouat Mine (_5_ ) . The s topes would be 
about 200 ft long and 170 ft high along 
dip. They would be separated horizon- 
tally by 20-ft-wide pillars. Raises 
would be bored from the level above. Ore 
haulage would be by battery motors on the 
intermediate levels and by trolley or 
diesel motor on the main haulage level. 
The ore would be moved to the main haul- 
age level by ore passes and then by motor 
to the coarse ore stockpile at the mill. 
About 10 pet of the ore would remain in 
the mine as ground support pillars. 

Mine-run ore would be crushed to minus 
3/8 in and ground to minus 35 mesh (minus 
0.02 in) in a rod mill. Regrinding would 
be done in a ball mill. The undersize 
material would be fed to the spirals in 
the gravity separation circuit. Mill 
heads are expected to assay about 21 pet 
Cr203, the concentrate about 40 pet 
Cr203, and the tails about 5 pet 0^03, 
for a recovery rate of 88 pet Cr203. 
About 46 pet of the feed material would 
report to the concentrates. 

The grinding and gravity concentrating 
processes for chromite would use no chem- 
icals ( 6_) . The quality of the water is 
expected to be approximately the same as 
that of the surface water in the vicin- 
ity. Tailings would be piped about 1.5 
miles north of the mine site to a tail- 
ings dam at the St rat ton Ranch area 
(fig. 4). 

The concentrates would be agglomerated 
to a plus 8-mesh (1/8-in) size and fed 
to a sealed, submerged electric arc fur- 
nace to produce high-carbon ferrochrome. 
This ferrochrome would be acceptable for 
use in the production of austenitic 
stainless steel (12). At the present 
time, no steel smelter in the United 
States is known to use this process; how- 
ever, at least one smelter in Japan does 
have such a process. 

PGM 

The two sizes selected for PGM opera- 
tions were 1,000 tpd and 4,000 tpd ore. 



In general, operations of these sizes 
would fill a portion of the domestic need 
for PGM under normal and severe crisis 
scenarios, respectively. Other consid- 
erations, such as size of reserves and 
the physical characteristics of the ore, 
also entered into the size selection 
process. 

For the 1,000-tpd case, mining would 
be by shrinkage s toping. Rubber-tired 
vehicles would be used to haul ore and 
waste from the mine. Waste rock would 
be stored in a dump at the mine por- 
tal. Waste rock production would be ex- 
pected to be about 150 tpd. Mine life 
is estimated conservatively at 20 yr. 
Figure 5 shows the location of proposed 
facilities. 

The Minneapolis Adit (fig. 6) will be 
the main entrance to the mine and serve 
as the main haulageway. The mine waste 
rock dump would be located near the por- 
tal. The mill, shop, and other surface 
facilities would be located nearby, as 
shown in figure 5. 

PGM milling would be by the froth flo- 
tation method using a low-pH process. 
Ore would be crushed, ground, and floated 
using a potassium amyl xanthate collector 
and a polyglycol ether frothing agent. 
Carboxy methyl cellulose and CuSO^ would 




FIGURE 5. - Plan map of PGM mine-mill facilities. 




FIGURE 6. - Minneapolis Adit, main haulage for PGM operations. 



be added as conditioners. Additional in- 
formation on the milling process can 
be found in other Bureau publications 

( n-u) . 

Tailings would be disposed of in a 
lined tailings pond at the same site 
(fig. 5). Approximately 87 pet of the 
processed mill feed would be tailings. A 
tailings dam would be constructed using 
the centerline method (15) . 

Several changes are needed in order to 
achieve 4,000-tpd capacity in PGM mining 
and milling operations. In-mine crushing 
and belt haulage would be used instead 
of rubber-tired haulage to transport ore 
out of the mine. A decline from the West 
Fork area to the ore zone would be added 
to gain access to additional reserves. 
Waste rock would continue to be hauled by 
rubber-tired vehicles to the dump site 
near the portal, but the amount would 
increase to about 600 tpd. 

The tailings area at the Minneapolis 
Adit is not large enough to store 20 yr 



of production at 4,000 tpd. Utilization 
of cut-and-fill s toping would reduce the 
amount of material in the tailings pond 
by returning about 50 pet of the material 
to the stopes as backfill, but even then, 
the tailings area at the Minneapolis Adit 
is barely large enough to accommodate 
20 yr of production. 

Therefore, the tailings area would be 
moved to a secondary site known as Hertz- 
ler Ranch (figs. 7-8), which is large 
enough to store this amount of tailings. 
This site was selected based on an in- 
depth study of alternative tailings pond 
sites in the area (10). 

The mill would remain located near the 
Minneapolis Adit. It would use the same 
flotation process described above. The 
tailings would be separated into two size 
fractions. The coarse (150-mesh) materi- 
al would be slurried and pumped back into 
the mine as backfill material. The fine 
fraction would be slurried and pumped to 
the Hertzler Ranch tailings pond. 




FIGURE 
rate. 



Contour interval, 
200 ft 

7. - Plan map of tailings pond gt Hertzler Ranch area for PGM operations, high production 



The tailings slurried to the pond would 
contain an inadequate amount of coarse 
material for dam construction, so borrow 
material from the area would be used. 
Suitable material for dam construction 
can be removed from the pond site before 
mining commences. The impermeable geo- 
logic conditions at the Hertzler Ranch 
site make pond lining unnecessary (10). 

Concentrated ore from both the 1,000- 
tpd and 4,000-tpd operations would be 
shipped elsewhere for refining. Truck 



haulage would be 
concentrate. 



used to transport the 



NICKEL-COPPER 

An open pit is the mining method most 
likely to be used to extract Ni-Cu ore 
from the Basal zone of the Stillwater 
Complex. A proposed plan is to develop 
a section of this zone located within a 
large rotated block (faulted section of 
the complex) . This block also contains 



10 




FIGURE 8. - Hertzler Ranch area. 



Ni-Cuand PGM pond 




'Nye 



*°\ 




Ni-Cu pit i 



Beartooth t 
Ranch 



^Woodbine 
Campground 







<^^ ~/~ V_-^4]9f-l— l«J^J=-*= 




//h 


a^ i — i — * Columbus 




//?10r 


" 24 miles 


/ 






/A 

ond Iffy 




LEGEND 
Paved road 




Gravel road 


€ws 




*-^-t- Railroad 


s 




Slurry pipeline 

— < Mine adits 
© West Fork PGM (hypothetical) 


PGM mill 




© Level 5 Cr (existing) 


-«,4 




® Minneapolis (existing) 
@ Monte Alto (partially completec 
*® Photo locations 

A Figures 1 3 and 1 4 

8 Figure 15 

C Figure 16 

1 

i j 



Scale, mi 



FIGURE 9. - Plan map of combined operations, a hypothetical worst case. 



the chromite zones at the old Mouat Cr 
operation. Figure 9 is a surface plan 
view showing the potential open pit, 
dump, and processing facilities, as well 
as PGM and Cr operations included in a 
worst case scenario. The Ni-Cu mine life 
is expected to be 18 yr. 



The ore zone would be mined by standard 
open pit techniques using shovels and 
mine trucks. A rate of 27,500 tpd ore 
and 24,800 tpd waste is proposed. A pri 
mary crusher would be located at the east 
side of the pit. Crushed ore would be 
conveyed downhill at no more than a -16 



11 



slope. The conveyor would be enclosed 
and strong enough to withstand the depo- 
sition of overlying mine waste. At the 
base of the dump, a transfer station 
would direct ore toward the milling fa- 
cilities near river level. To the north 
a service road would be extended from 
the Mouat Mine road. Verdigras Creek 
(fig. 10) would be diverted above the pit 
and redirected north about 3,000 ft to 
Mountain View Lake. An equipment mainte- 
nance facility and mine truck parking 
would be located just north of the pit. 

Conveyed ore would be stockpiled adja- 
cent to the processing facilities. The 
mill feed rate would be 20,500 tpd, 7 
days per week. Initial processing would 
involve grinding the feed to minus 250 
mesh using semiautogenous mills and ball 
mills. Bulk sulfide flotation would be 



used to recover Ni and Cu. The rougher 
concentrate would be cleaned twice to 
remove Fe and insolubles. A total of 
19,500 tpd of rougher tails averaging 
0.075 pet Ni and 0.045 pet Cu would be 
disposed of in a tailings pond facility, 
and 940 tpd of cleaner concentrates would 
be sent to the leaching circuit. 

The proposed leach process would be 
similar to the two-stage Cl-0 2 leach cur- 
rently being tested by the Bureau (16). 
In a batch process , cleaner concentrate 
would be mixed with reclaimed water and 
recycled solutions. This pulp would be 
autoclaved, and CI and compressed air 
would be added. After 5 h, 94 to 99 pet 
of the Ni and Cu would be ionized in so- 
lution. The high-grade Ni-Cu solution 
would be recovered using wash water. 
A waste product amounting to 866 tpd, 




FIGURE 10. - Verdigras Creek. 



12 



containing Fe and gangue minerals , would 
be disposed of in the tailings pond. 
Copper would be electrowon, and nickel 



would be precipitated; 40 tons of Ni and 
34 tons of Cu would be recovered daily at 
78- and 67-pct recoveries, respectively. 



LAND ISSUES 



The land issues category contains the 
most significant environmental issues 
found in the study. Mining, milling, and 
refining typically involve significant 
land use changes. 

Solid wastes, including waste rock from 
mining, tailings from milling, and sludge 
from Cr smelting, would create a dispo- 
sal problem that would have its primary 
effects on the land. Choice of disposal 
sites would be a significant problem in 
the Stillwater Complex. Much of the area 
is too mountainous, at too high an eleva- 
tion, or situated on unstable geologic 
features, and would not make good dispo- 
sal sites. 

The chemical composition of the tail- 
ings to be generated is not cause for un- 
due concern. However, the sludge from 
ferrochrome production might require spe- 
cial handling and storage methods to en- 
sure that any potentially hazardous com- 
pounds are properly contained. 

In the following sections, these land 
issues are discussed: tailings dispo- 
sal, smelter waste, waste rock, land use 
changes, visual impact, and reclamation 
plans. 

TAILINGS DISPOSAL PLANS 

The tailings dams for all disposal 
plans would be instrumented and moni- 
tored. Instrumentation would include 
piezometers to monitor the phreatic sur- 
face within the dams. Frequent inspec- 
tion and periodic surveys of the dam face 
would be conducted to detect any dam 
movement. Monitor wells, installed down- 
drainage from the dams, would be sampled 
periodically to check for seepage. 

Chromite Tailings 

For both scenarios, the chromite tail- 
ings pond would be located at the Strat- 
ton Ranch site (fig. 4). The pond would 
have an average height of 50 ft and a 
maximum height of 75 ft, and would occupy 



approximately 40 acres at the end of the 
mine life. 

The tailings dam would be constructed 
of tailings using the upstream method. 
A cross section of a typical upstream dam 
is shown in figure 11. This type of con- 
struction is the least expensive and 
should result in a stable dam since there 
are relatively few fines in these tail- 
ings . Seepage through or under the dam 
would be collected by a toe drain and re- 
turned to the pond. The chemical compo- 
sition of chromite tailings is relatively 
inert, making pond lining unnecessary. 

In the event of combined Cr, PGM, 
and Ni-Cu operations, the large Hertzler 
Ranch site (fig. 9) would be used, and 
the Stratton Ranch would not be needed. 
The amount of tailings generated by Cr 
operations would be negligible compared 
with the amounts generated by PGM and Ni- 
Cu operations. 

PGM Tailings — Minneapolis Adit Site 

Two different areas have been chosen 
for PGM tailings disposal, depending on 
the scenario. For the low-end scenario, 
the Minneapolis Adit site would be used 
(figs. 5-6). This pond would have an 
average height of 80 ft and a maximum 
height of 100 ft, and would occupy an es- 
timated 75 acres. For the high-end sce- 
nario, the Hertzler Ranch site would 
be used (fig. 8). This pond would have 
an average depth of 40 ft and a maximum 
height of 75-ft, and would occupy an es- 
timated 380 acres. 

In the low-end scenario case, the tail- 
ings dam would be constructed using the 
centerline method of construction (fig. 
11). This type of dam would be more ex- 
pensive than an upstream-constructed dam, 
but would be structurally stronger. This 
dam would be relatively high and would be 
located near a county highway, so struc- 
tural integrity would be important. This 
dam would be constructed with a blanket 
or toe drain to keep the phreatic surface 



13 



£ 



Pond 



>& 



\\\ \\\ 



/// \\\ 

Fine tailing (slimes 

J^ * * « 

* wm7 ' ^~ mv&zmr 

^ Original ground 
surface 



Coarse tailing (sands) 




Starter dam 



UPSTREAM SPIGOTING METHOD 



Cyclone 



Water and slimes 
released to pond, 



Sands distributed and compacted 
on downstream slope 




Slimes 



Initial dike 
(compacted in layers) 



CENTERLINE METHOD 
FIGURE 11. - Upstream and centerline methods of constructing tailings dams. 



in the dam at acceptable levels. Any 
seepage would be returned to the pond. 

The bottom surface of the pond and 
the upstream face of the dam would be 
lined to minimize seepage under the pond 
and possible contamination of ground 
water. Monitor wells installed down- 
drainage from the pond would be sampled 
periodically to check for seepage. 

PGM Tailings — Hertzler Ranch Site 

In the high-end scenario for PGM opera- 
tions, the tailings area would be located 
at the Hertzler Ranch. Since cut-and- 
fill stoping is the mining method in this 
scenario, borrow material would be used 
to construct the tailings dam. This ma- 
terial would be scraped from the pond 
area at the beginning of operations. The 
pond location was chosen to minimize dam 
size and height. The tailings dam would 



be constructed using standard earth dam 
techniques (15) . 

The impermeable shale that underlies 
the Hertzler Ranch site makes a liner un- 
necessary. Instead, a toe drain and sump 
would collect any seepage and return it 
to the pond. 

A perennial stream running in Robinson 
Draw must be diverted around the tail- 
ings area. This diversion, shown in fig- 
ure 7, would reduce the amount of runoff 
water the pond and dam will be required 
to handle. 

A pond liner should be unnecessary, but 
the sand and gravel overlying the pond 
would be scraped off to minimize leakage 
under the dam. Geologic data indicate 
that an average of 15 ft of alluvium 
needs to be removed to expose the shale. 
Monitor wells, piezometers, and surveys 
would ensure that the pond and dam are 
performing properly. 



14 



Nickel-Copper Tailings 

Only two sites in the area are capable 
of holding the estimated 81 million yd 3 
(128 million tons) of tailings produced 
over the 18-yr life of the mine. These 
sites are the Hertzler Ranch and Horseman 
Flats, which could hold 100 million yd 3 
(155 million tons) and 159 million yd 3 
(252 million tons) of tailings, respec- 
tively. The Hertzler Ranch site is about 
6.5 miles north and down-drainage from 
the proposed Ni-Cu mill site (figures 7 
and 8) . The Horseman Flats site is about 
4 miles northwest of the mill site and 
about 850 ft higher in elevation, which 
would entail pumping the tailings uphill 
(fig. 9). At present, the Hertzler Ranch 
seems to be the most viable site since 
sufficient water is available from the 
Stillwater River for a mill at the pres- 
ent site. The major environmental prob- 
lems would apply to either tailings site. 

Combined Tailings 

In the event of combined Cr, PGM, and 
Ni-Cu operations, the Hertzler Ranch site 
would be used to contain tailings from 
all three operations. This pond would be 
an average of 75 ft high, be constructed 
in two terraces, have a maximum height of 
125 ft, and cover an estimated 650 acres 
at the end of mining. 

Two tailings dams would be constructed 
using tailings from the Ni-Cu and Cr 
operations. The first dam would be con- 
structed to form the upper terrace at 
5,000 ft elevation. The upper terrace 



would hold about 60 pet of the tailings. 
The lower terrace would crest at 4,900 ft 
elevation and contain the balance of the 
tailings. 

In order for all of the tailings gener- 
ated by combined operations to be con- 
tained on the site, all of the alluvium 
from the site must be removed and stock- 
piled. This is an estimated 425 million 
ft 3 of material, which would be used dur- 
ing reclamation at the end of mining. 

Both dams would be constructed using 
the centerline method described previous- 
ly. Instrumentation would be installed 
to ensure proper performance. The creek 
diversion mentioned earlier would be re- 
quired in this scenario, also. 

TAILINGS POND RECLAMATION 

Chromite Tailings 

The chromite tailings pond is expected 
to cover approximately 40 acres at the 
Stratton Ranch site at the conclusion of 
mining. The material should be relative- 
ly uniform and porous, and dry quickly. 
The tailings area would be contoured to 
more closely resemble natural surround- 
ings after it has dried. 

The tailings area from previous Mouat 
Cr mine operations has been successfully 
revegetated by The Anaconda Company (10) . 
That area has been seeded with a mixture 
of grasses and forbs, heavily fertilized, 
and irrigated periodically. Revegetation 
species were seeded at between 23 and 31 
lb of live seed per acre. Species used 
are listed in table 1. 



TABLE 1. - Revegetation species used in reclamation (10) 



Common name 


Scientific name 


Approximate seed rate 

(pure live seed), 

lb/acre 


Sheep fescue or Idaho fescue 




4-5 




4-5 
4-5 


Festuoa ovina or Festuca 
idahoenis. 


3-4 
3-4 






3-4 
.5 






.5 




2-3 



15 



A similar program of revegetation would 
be expected to be successful on tailings 
generated by future Cr raining. To com- 
pletely revegetate this area would re- 
quire 2 to 3 yr. 

PGM Tailings 

For the low-end production rate of 
1,000 tpd, the tailings pond would be lo- 
cated at the Minneapolis Adit site (fig. 
5) and would occupy about 75 acres. Max- 
imum height would be about 100 ft. The 
PGM tailings would contain a greater pro- 
portion of fines than the chromite tail- 
ings and would not dry quickly. 

Once the tailings dam reaches its maxi- 
mum height, revegetation of the dam face 
could begin. The relatively steep slope 
of the dam face (approximately 30 pet) 
would probably make more involved reveg- 
etation efforts necessary. Techniques 
such as straw mulch crimping and netting 
would probably be used to help hold the 
seed until germination. 

Revegetation of the tailings pond sur- 
face would have to wait until it has 
dried sufficiently. Until then, chemi- 
cal dust suppressants could be applied to 
reduce fugitive dust. Mine waste rock 
could be spread over the surface of the 
area during the winter to increase its 
load-bearing capacity. Soil scraped from 
the site before the pond was constructed 
could then be spread over the surface of 
the pond. If soil is not used to cap the 
pond, revegetation would be much more 
difficult and expensive. Fertilizer, 
mulching, and irrigation rates would be 
increased. Biomass production would be 
lower, lengthening the time to full rec- 
lamation by as much as 2 yr. 

For the high-end production rate of 
4,000 tpd, the Minneapolis Adit tailings 
pond location is not large enough, so the 
Hertzler Ranch site is assumed to be 
used. A detailed reclamation plan has 
already been established for this site 
( 10) . A brief description of it follows. 

After operations cease, the tailings 
area would be recontoured into a gentle 
dome. This will encourage precipitation 
to drain off the tailings instead of 
percolating through them. Approximate- 
ly 2 ft of waste rock from the mining 



operation would be used to cap the area 
and increase its load-bearing capacity. 
Approximately 18 in of topsoil and sub- 
soil scraped from the site before the 
pond was constructed would be spread over 
the rock. Revegetation using the species 
listed in table 1 along with a few addi- 
tional trees and shrubs would complete 
the reclamation. After reclamation, the 
area should be similar to the current 
stony grassland ( 17 ) and is expected to 
be suitable for grazing, the current land 
use for that area. 

Nickel-Copper Tailings 

Reclamation would be the same as for 
the PGM tailings reclamation plan dis- 
cussed in the previous section, but on a 
larger scale. After operations cease, 
recontouring to a more natural shape 
would commence. Waste rock from the open 
pit would be used to cap the area. Top- 
soil stripped from the pond area before 
construction would be spread over the 
rock. Revegetation using species listed 
in table 1 and a few trees and shrubs 
would complete the reclamation. The area 
would appear similar to the present area 
but would be 100 to 150 ft higher. 

FERROCHROME SMELTER WASTE 

The ferrochrome smelter produces two 
types of solid waste that require dis- 
posal: sludge from venturi scrubbers 
and slag from the smelter. Of the two, 
sludge is the more difficult prob- 
lem because of the high organic con- 
tent. Smelter slag is essentially vit- 
rified silicates and should be fairly 
nonreactive. 

The ferrochrome smelter emits signif- 
icant amounts of gas containing partic- 
ulates. The particulates are removed 
from the gas by a venturi scrubber as a 
sludge. 

Sludge recovery from the venturi scrub- 
bers would amount to 30 tpd and 72 tpd 
(11,000 tpy and 26,000 tpy) for the low 
and high production rates, respectively. 
The sludge, after filtering to remove wa- 
ter, would be permanently stored on-site 
and would require a double-lined pit. 
This 40-ft-deep pit would be made by 



16 



excavating to 20 ft of depth and bounding 
the excavation by 20-ft-high walls. An 
area of 3,500 ft 2 /yr is needed for the 
low-end scenario and 8,500 ft 2 /yr for the 
high-end scenario. Up to 8 wt pet of the 
sludge would be organic material ( 18) . 
Monitor wells would be installed to warn 
of seepage. 

Alternate methods of handling the 
sludge would include recycling it back to 
the briquetting operation, disposing of 
it by including it with the mill tail- 
ings, or possibly using it in making 
blocks for permanent solid storage. 
These alternate methods require further 
study to identify their potential. 

Organic matter emitted can be par- 
tially captured using scrubbers for 
closed or sealed furnaces and baghouses 
for open furnaces. These control systems 
recover a solid waste sludge and dust; 
respectively. A sealed furnace and 
scrubber system, as previously mentioned, 
was chosen for the ferrochrome produc- 
tion segment of the chromite operation 
because a higher percentage of organic 
matter would be recovered. In a previ- 
ous study (18), five ferroalloy furnaces 
were tested for generation and emission 
of particulate and organic matter. Even 
though no high-carbon-f errochrome-produc- 
ing furnaces were tested, general results 
comparing open and closed (sealed) fur- 
naces are applicable. It is reported 
that scrubbers are much more efficient 
than baghouses in recovering organic 
matter. The major evidence is that the 
covered furnaces tested generated more 
organic matter per megawatt hour but 
emitted less into the atmosphere after 
the scrubber. Open furnaces tested gen- 
erated less per megawatt hour but emitted 
more into the atmosphere after the 
baghouse. 

Concentrations of benzo(a)pyrene (BaP) 
emitted as exhaust gas into the atmos- 
phere from three ferroalloy plants ex- 
ceeded the discharge multimedia environ- 
mental goals (DMEG) of the EPA, whose 
recommended value is 0.02 p.g/m 3 ( 18) . 
DMEG's are used as reference points and 
are not regulatory policy. Sampling in- 
dicated none of the solid wastes would be 
classified as hazardous, although all but 



one operation exceeded DMEG-re commended 
values for land disposal of BaP. Treated 
water discharge from the two covered 
smelter furnace control systems contained 
no polynuclear aromatics. Biphenyl was 
found in the emission samples from the 
two covered furnaces, suggesting the com- 
pound may also be present in discharged 
solid wastes. In chlorination treatment 
systems there is a possibility of form- 
ing polychlorinated biphenyls from the 
biphenyls. 

The dewatered scrubber sludge accumu- 
lated from the waste water treatment sys- 
tem would contain various organic com- 
pounds. Until additional information is 
available regarding safe disposal, all 
smelter sludge would be retained as solid 
waste. 

Slags are vitrified silicates similar 
in content to scrubber sludge. Molten 
slag would be dumped into pits open at 
one end to permit removal after quench- 
ing and granulation (18) . The slag pit 
should be concrete-lined and sealed to 
prevent pollution of ground water. Ex- 
cess quenching water would be contained 
within the pit and used during the next 
slag dumping. The granulated slag can be 
stockpiled as waste or used as road base. 

Reclamation of smelter slag and scrub- 
ber sludge would occur during operations, 
and very little reclamation would be 
needed after operations cease. Reclama- 
tion of slag would be a fairly simple 
process. The dump size would be pre- 
planned and the pile shaped to have a 
more natural appearance. Dumping and 
reclamation would be similar to the oper- 
ations of the Ni-Cu mine waste dump dis- 
cussed in the next section. 

Smelter sludge from the venturi scrub- 
bers would be stored in double-lined 
pits. Several pits would be needed al- 
though the number would depend on opera- 
tion size. As each pit is filled it 
would be covered with an impermeable 
liner similar to the one used underneath 
the waste. Monitor wells would be in- 
stalled to warn of seepage. Topsoil 
would be placed over the liner. Hydro- 
mulching and tree planting would reduce 
erosion. 



17 



WASTE ROCK 

A method has been proposed for dumping 
Ni-Cu mine waste rock, that would lessen 
the visual impact. Waste would be trans- 
ported to the base of the dump area and 
placed in low lifts or terraces. Three 
main advantages of using this method 
would be the ability to adjust the dump 
slope to conform to the natural topogra- 
phy, the ability to revegetate the dump 
slope after each lift is completed, and 
the ability to create a more stable dump. 

Operations of this method would in- 
volve transporting waste by truck from 
the pit, downhill to the base of the pre- 
planned dump area. Each lift would be 
about 10 ft high or higher, depending on 
mine truck size and dumping method. Ini- 
tial dumping of each lift would be at the 
peripheral crest of the previous lift to 
form a 10-ft-high berm. 

For this plan to work properly, trucks 
must dump waste on a given lift while 
positioned on that lift (fig. 12). The 
trucks would then be partially hidden 
behind the initial berm, reducing vis- 
ual impact. A bulldozer would intermit- 
tently level the spoils piles to provide 
a drivable base for the following lift 
construction. A hydromulch sprayer would 
be used to establish vegetation. Small 
trees similar to species in the area 
would also be planted. 

In the conventional technique, waste 
rock would be dumped near the pit in a 
manner such that the face of the waste 
pile is constantly "active and cannot be 
vegetated. Each load would be dumped 
over the previous load, but the dumping 
elevation would be kept constant and the 
waste pile would be extended out horizon- 
tally. Some of the dump may be vegetated 
during operations after that area becomes 



inactive, but a large percentage of the 
dump would remain active until operations 
cease. 

Reclamation would be done both during 
and after operations cease. Erosion and 
sedimentation impacts would differ de- 
pending on which of the two dumping meth- 
ods is chosen. Conventional dumping 
techniques make vegetation efforts impos- 
sible until after operations cease. The 
multiple-lift approach allows vegetation 
during operations, reducing erosion and 
sedimentation of waters downslope. 

The pit could be recontoured by blast- 
ing to form a more continuous slope rath- 
er than leaving benches. A more natural 
talus slope appearance would result. 
Another approach is to leave the benches 
intact and lay topsoil on each level. 
Grasses and trees could be planted to 
minimize erosion as well as to improve 
the visual appearance. The stream diver- 
sion would be removed, allowing Verdigras 
Creek to flow into the pit, forming a 
small lake similar to Mountain View Lake. 
Water redirected into the pit would need 
a permanent channel. Some blasting and 
rock removal may be needed. 

LAND USE CHANGES 

Approximately 25,000 acres in and 
around the Stillwater Complex were ana- 
lyzed for major land use categories (17). 
About 50 pet of the area is undeveloped 
national forest, wilderness area, and 
private land. The land serves as wild- 
life habitats and as camping, hiking, 
fishing, and hunting areas. Agriculture 
uses about 42 pet of the area; livestock 
grazing is the most prevalent agricul- 
tural use. Residential, recreational, 
and mining activities make up the re- 
mainder of land uses of the area. Most 



Mine truck 



Bulldozer 



Hydromulcher 




FIGURE 12. - Waste rock terracing method. 



18 



people live in four communities: Nye, 
Dean, Fishtail, and Absarokee. Approxi- 
mately 50 vacation homes are located in 
the area, as well as 2 commercial guest 
ranches and 2 campgrounds. Mining and 
exploration activities make up about 
1 pet of the land use in the study area. 

Mining of Cr, PGM, and Ni would repre- 
sent a significant change in land use for 
the region. Tailings areas would be lo- 
cated on grazing land and remove it from 
service for a period of time ranging from 
15 to 30 yr. After the mines are closed, 
the tailings areas can be revegetated to 
be used again for grazing. The undevel- 
oped land at the Ni-Cu open pit would be 
permanently altered. Reclamation after 
mining would minimize impact. Other land 
that would be used for mine, mill, and 
smelter building sites would be changed 
from agricultural and residential use to 
industrial use. 

Since infrastructure such as roads , 
transmission lines, and rail would be 
upgraded, it is likely that other small 
businesses and industries would choose to 
locate in the area. Many of these busi- 
nesses would probably supply goods and 
services to the growing mining community. 

In total, Cr operations would require 
about 90 acres for the low-end scenario 
and 125 acres for the high-end scenario. 
PGM operations would require 160 acres 
for the low-end scenario and 400 acres 
for the high-end scenario. Nickel-copper 
operations would require 900 acres. The 
total land used for all mining opera- 
tions, if all were conducted simulta- 
neously, would be 1,425 acres, or about 
6 pet of the land in the study area. 

VISUAL IMPACTS 

The major visual impact would result 
from the Ni-Cu pit and dump, which cover 
a total of about 350 acres. The other 
significant visual impact would be from 
the ferrochrome smelter and its tall 
stack. The remaining facilities would 
create limited and local visual impacts. 

The Ni-Cu pit and dump would be visi- 
ble for several miles in the Stillwater 
Valley. It would be the only facility 
visible from the Beartooth Ranch, Wood- 
bine Falls (0.5 mile east of Woodbine 



Campground) , and the Absaroka Beartooth 
Wilderness. The ferrochrome plant and 
the Ni-Cu pit and dump would be visible 
for at least 6 miles downstream. Other 
features such as the tailings dams and 
mill facilities would only be visible 
from the road for short distances (figs. 
13-16). 

The chromite tailings would cover an 
area of about 40 acres. The PGM tailings 
would cover 75 acres for the low-end case 
and 380 acres for the high-end case. The 
Ni-Cu tailings dam would cover about 350 
acres. The tailings dams would be up to 
125 ft high. The Ni-Cu tailings area 
would be visible from parts of the road 
leading to the Benbow Mine. 

Solid waste from the ferrochrome smelt- 
er would eventually occupy an area of 
about 20 acres. A 30-day supply of feed 
material for the smelter would be stored 
on 1 acre of land near the smelter. Some 
of the material, such as the coal char, 
may be covered or stored in large bins 
for protection from the weather. 

Other items that will visually impact 
the area are as follows: (1) a pipeline 
for Ni-Cu tailings, which would be visi- 
ble from the road between the Ni-Cu mill 
and the Hertzler Ranch tailings site, 
(2) a railroad spur, and (3) power lines, 
which would be visible between the city 
of Columbus and the ferrochrome smelter, 
a distance of about 35 miles. 

To a large extent , visual impacts can- 
not be avoided, owing to limited siting 
options and high visibility throughout 
the valley. Use of blend-in colors for 
buildings and use of the multiple-lift 
waste rock disposal method described ear- 
lier should reduce negative impact. 

SUMMARY OF LAND ISSUES 

The most significant land issues iden- 
tified in this study are — 

1. Disposal of tailings, including 
sound dam design and reclamation. 

2. Disposal of ferrochrome smelter 
waste. 

3. Changing land use patterns from 
agriculture and recreation to mining and 
mineral processing. 

Adequate technology exists to permit 
sound tailings pond construction and 



19 




(D 

=> 



(D 

E 
a 
U 



u 

-o 
o 



Q. 
O 



O 

Q_ 

o 
(/) 
u 



O 







0) 

E 
a 
U 



Q. 
O 



E 
o 
u 

o 
I/) 
u 



D 

- 

> 



LU 
Qi 

ID 
O 



20 



Dumps 




FIGURE 15. - Visual effects of Ni-Cu open pit from Beartooth Ranch. Camera location is shown 
on figure 9 (£>)• 



■*,:* \ 






Pit 



FIGURE 16. - Visual effects of Ni-Cu open pit from Woodbine Falls. Camera location is shown 
on figure 9 (C). 



21 



reclamation. Additional research is 
needed to more accurately describe the 
nature of ferrochrome smelter solid 
waste, before sound disposal plans for 
permanent storage of this waste can be 



drawn up. The noted change in land use 
patterns is largely unavoidable during 
the term of active mining. After mining, 
land use would return to earlier patterns 
of agriculture and recreation. 



WATER ISSUES 



Water quality is very important to res- 
idents and visitors and is quite likely 
the most important environmental issue in 
this area. The generally high baseline 
water quality is a source of pride to 
residents. Fishing is a major recre- 
ational activity. In general, water is- 
sues associated with the proposed mines 
can be dealt with effectively. 

In this section, baseline water qual- 
ity, control of mine drainage water and 
tailings pond water, and water treatment 
for the Cr smelter are discussed. 

SURFACE WATERS BASELINE QUALITY 

Sample analyses from three separate 
studies are combined in this section to 
show the overall surface water quality of 
the Stillwater Complex. Anaconda con- 
tracted Camp Dresser and McKee, Inc., to 
complete a baseline environmental study 
as part of Anaconda's operating permit 
application for its proposed Stillwater 
project (18). Hydrologic monitoring en- 
tailed monthly, biweekly, and irregularly 
timed measurements of streamflow for a 
1-yr period (June 1980 to June 1981). 
Five stations were established on the 
Stillwater River and seven stations on 
its tributaries. These samples points 
are shown on figure 17 as numbers 18 and 
20-30. 

The Stillwater PGM Resources Co. con- 
tracted Beak Consultants, Ltd., to pre- 
pare a baseline environmental study of 
the East Boulder River and Dry Fork areas 
( 19) . Thirty surface water sample loca- 
tions were used in Beak's report, but of 
these only eight were used in the Bu- 
reau's analysis. These samples are shown 
on figure 17 as numbers 4 through 11. 
Sampling was conducted over a 1-yr period 
beginning April 1981 and ending April 



1982. Each station was monitored up to 
17 times in that year, which was similar 
to the sampling done by Anaconda. 

The Bureau sampled surface waters dur- 
ing the month of June 1984 specifically 
for this report. An attempt was made to 
fill in gaps from previous studies in or- 
der to gain a picture of the water qual- 
ity of the entire Stillwater Complex; the 
one-time sampling was used to gain addi- 
tional data points. The 14 Bureau sam- 
ples are shown in figure 17 as numbers 
1-3, 12-17, 19, and 31-34. 

Although the two industry surface water 
studies involved analyzing samples for 
many parameters, the Bureau analysis con- 
cerns only parameters that have been 
given regulatory standards, (table 2). 
The Bureau analyses are limited to only 




LEGEND 

X Mines 
@ Gish (Cr) 
@ Mouat (Cr) 
(S) Mouat (Ni-Cr) 
@ Stillwater (PGM) 
@ Benbow (Cr) 

G- Water sample 



FIGURE 17. - Water sample locations. 



22 



part of this list, as identified in table 
2. The industry surface water studies 
included all parameters listed. 

TABLE 2. - Water quality regulatory 
standards (20) 



Parameter 



Standard, ppm 



Ag 1 


0.05 


As 


.05 


Ba 1 


1.00 


Cd 


.01 


CI 1 


250 


Cr 


.05 


Cu 


1.00 


F 1 


2.4 


Fe , ..... 


.3 


Hs 


.002 


Mn 


.05 


Pb 


.05 


Se 


.01 


Zn 


5.00 


Sulfate 1 


250 




10 


Total dissolved solids 1 ... 


500 
2 100 




5 



^ot analyzed by Bureau. 
2 Number of bacteria per 100 mL. 



Surface water samples that exceeded the 
regulatory standards are given in table 
3. The data given in this table repre- 
sent the maximum values obtained during 
the 1-yr period. Parameters that ex- 
ceeded the standards were Cd, Cr, Fe, Mn, 
Pb, fecal bacteria, and turbidity. 

Cadmium standards at eight sample sites 
exceeded in the Stillwater River Valley. 
Seven of these assayed 0.02 ppm Cd. Sam- 
ple 25 had the highest value at 0.03 ppm, 
indicating a higher background for Cd in 
the West Fork drainage. Sample 12, lo- 
cated farther up the West Fork, did not 
show Cd values exceeding regulatory 
standards. It is believed that high Cd 
values in the surface water are the re- 
sult of natural background and are not 
due to any point source discharge (19). 
Surface water samples taken during peak 
flow periods (May and June) show highest 
metal concentrations. This may be due to 
higher concentrations of suspended sol- 
ids; only Bureau samples were filtered to 
remove the solids. Manganese, chromium, 
lead, and fecal values exceeded regula- 
tory standards during peak flows in sev- 
eral of Anaconda's samples. Sample 32 (a 
Bureau sample) , which assayed 0.082 ppm 
Cr (greater than regulatory standards), 



TABLE 3. - Surface water samples exceeding regulatory standards 



Sample 1 


Element , ppm 


Fecal 
coliform 2 


Turbidity, 3 




Cd 


Cr 


Fe 


Mn 


Pb 


NTU 


5 


a 

a 

a 

0.02 

.02 

.02 

a 

.02 

.03 

.02 

.02 

a 

.02 

a 


a 
a 
a 
a 
a 
a 
0.14 
a 
a 
a 
a 
a 
a 
.082 


a 
a 
a 
0.57 
1.3 
a 
16 
.31 
1.1 

a 

1.6 

.57 

a 

a 


0.06 

.06 

a 

.09 

a 

a 

.28 

a 

a 

a 

a 

a 

a 

NA 


a 
a 
a 
a 
a 
0.09 
a 
a 
a 
a 
a 
a 
a 
a 


a 
a 
a 
a 
a 
a 
a 
a 
a 
a 
920 
a 
a 
a 


a 


6 


a 


7 


14.0 


18 


a 


20 


a 


21 


a 


23 


a 


24 


a 


25 


a 


27 


a 


28 


a 


29 


a 


30 


a 




NA 



a Did not exceed standard. NA Not analyzed, 
Sample locations are shown on figure 17. 
2 Number of bacteria per 100 mL. 
3 Analyzed by Beak Consultants, Ltd. 



23 



was also taken during peak flow. At this 
location, an intermittent stream was 
flowing through a mine waste dump at the 
Benbow chromite mine. This sample was 
filtered to remove suspended solids. 
High Cr values may be due to chromite 
dumps and abandoned tailings ponds where 
fresh water is able to filter through. 

High Mn and turbidity values from sam- 
ples 5 through 7 (19) may also be a re- 
sult of peak flow. Generally high values 
from Cd and Fe throughout the year indi- 
cate natural background and not a point 
source. Fecal coliform exceeded regula- 
tory standards in sample 28. The high 
coliform counts reflect the presence of 
cattle in the area. Water quality of the 
Stillwater River is characterized as good 
to excellent, while its tributaries are 
characterized as poor to good. Surface 
water quality of the East Boulder River 
is rated generally high at upper eleva- 
tions but deteriorates somewhat with 
downstream distance (19). 

In utilizing all sample data, an anal- 
ysis of the surface water quality of the 
entire Stillwater Complex can be at- 
tained. The quality of water from major 
rivers draining north through the complex 
is good to excellent. High metal values 
from tributaries in the complex indicate 
local sources. Downstream at lower ele- 
vations where cattle grazing is promi- 
nent, degradation of water quality is 
evident. The tributaries within and to 
the south of the complex can be classi- 
fied as poor to good. 

MINE DRAINAGE WATER QUALITY 

Mine drainage from several adits in the 
Stillwater Complex was sampled and ana- 
lyzed for water quality. Samples were 
taken by the Bureau from the Benbow Mine, 
the Mouat Mine, the Verdigras Creek Adit, 
and the Gish Mine. Samples were taken by 
Camp Dresser and McKee ( 17 ) from the Min- 
neapolis Adit, the Mouat Mine, and the 
Verdigras Creek Adit. 

Samples taken by the Bureau were taken 
in accordance with EPA-recommended meth- 
ods (20) . Samples were filtered at 0.45 
(j.m and acidified with HNO3. Samples were 
analyzed for 16 cations, as listed in 



table 2. Of the samples taken by the 
Bureau, only one from the Mouat Mine ex- 
ceeded water quality criteria for any 
constituent. A Cr level of 0.082 ppm was 
measured in this sample. The EPA cri- 
terion for Cr is 0.05 ppm. EPA water 
quality criteria are stated in terms of 
total Cr (both hexavalent and trivalent). 
In its hexavalent state, Cr has been 
shown to be toxic and is suspected of 
being carcinogenic ( 21 ) . Hexavalent Cr 
is known to cause nasal irritation, and a 
positive correlation between cancer and 
exposure to hexavalent Cr has been noted. 
Trivalent Cr, the other common valence 
state, has been shown to be much less 
toxic and is not suspected of being 
carcinogenic. 

Samples taken by Camp Dresser and McKee 
indicated that a few constituents regu- 
larly exceeded EPA criteria. Minneapolis 
Adit samples had no constituent analyses 
that averaged above EPA criteria. Mouat 
Mine sample averages exceeded EPA crite- 
ria for Fe, Mn, and Se. Verdigras Creek 
Adit sample averages exceeded EPA crite- 
ria for sulfate, Fe, and Mn (19). The 
Verdigras Creek Adit is located in the 
Basal zone of the complex (fig. 1). This 
area contains sulfides, and the water is- 
suing from this adit reflects the compo- 
sition of the rock in the area. 

In general, mine drainage samples ex- 
hibited water quality higher than might 
be expected. Exceptions to this were 
rare. Sulfides in the PGM zone are a 
relatively low proportion of the ore, and 
water running through the Minneapolis 
Adit has little opportunity to acquire 
significant metal content. The unreac- 
tive nature of chromite in the Benbow, 
Mouat, and Gish Mines contributes to the 
low metals content of water issuing from 
these adits. The Verdigras Creek Adit is 
located in the more chemically reactive 
Basal zone, and the water issuing from 
this adit is of lower quality. 

In all samples, the pH was near neu- 
tral. This is due to the lack of pyrite 
in the rocks of the Stillwater Complex. 
The neutral pH contributed to the low 
metal concentrations found in mine drain- 
age water since solubility of most .metals 
is very low at neutral pH. 



24 



NEW SOURCE PERFORMANCE STANDARDS (11) 

Waste water discharges from mining, 
milling, and smelting activities in the 
Stillwater Complex would be regulated by 
the Clean Water Act, New operations 
would be considered "new sources." Regu- 
lations concerning effluent limitations 
were issued December 3, 1982. New source 
performance standards are the most strin- 
gent, because new mines and mills would 
"have the opportunity to install the best 
and most efficient waste water treatment 
technologies." 

The ore mining category has been di- 
vided into subcategories covering various 
ores and processes. There are existing 
subcategories for Ni mining and ferro- 
chrome production. A new subcategory for 
Pt mining was created recently; however, 
no subcategory for Cr mining currently 
exists. Both the Ni and Pt ore subcate- 
gories have been reserved, meaning that 
final determinations of effluent limi- 
tations will be set by the permitting 
authority (Montana Department of State 
Lands) on a case-by-case basis. New 
source performance standards for Ni and 
Pt mining have been issued in final form 
and are outlined in tables 4 and 5. 
Mines and mills processing more than 
5,000 tons of Ni ores in 1 yr have efflu- 
ent limitations listed in table 4. Mines 
and mills processing Pt ores (other than 
placer deposits) have effluent limita- 
tions listed in table 5. 

New source performance standards for 
froth flotation mills require a zero dis- 
charge. Both the Pt and Ni operations 
discussed in this report would use froth 
flotation and would be subject to this 
requirement. Chromium operations use a 

TABLE 4. - New source performance 
standards for Ni mining and 
milling, parts per million (11) 



TABLE 5. - New source performance 
standards for Pt mining and 
milling, parts per million (11) 



Parameter 


24-h max 


30 


-day av 


Total sue 


>pended 


30 

1.0 

.1 

.3 

1.0 

1.0 




20 


As 


.5 


Cd 


.05 


Cu 


.15 


Pb 


.5 




.5 



Parameter 

Cd .T. 

Cu 

Hg 

Pb 

Zn 



24-h max 


30-day av 


0.10 


0.05 


.03 


.15 


.002 


.001 


.6 


.3 


1.5 


.75 



gravity process and might not be subject 
to it. 

Zero discharge means that all process 
water must be contained within the mill- 
tailings pond circuit. The mill must not 
discharge waste water anywhere except to 
a contained tailings pond where excess 
water would evaporate. Seepage through 
the tailings dam or under the pond must 
be prevented or recovered. 

There are two exceptions to this re- 
quirement. If contaminants that inter- 
fere with milling tend to build up in the 
closed circuit, then a "bleed" stream may 
be allowed, subject to the limitations 
given in tables 4 and 5. If a 10-yr, 
24-h storm occurs, a temporary discharge 
of tailings pond water may be allowed, 
subject to limitations given in tables 4 
and 5. 

It is expected that Cr, Ni , and PGM 
operations would be required to adhere to 
the zero discharge requirement and that 
they would be capable of meeting it. 

FERROCHROME SMELTER WASTE WATER 

Scrubbers used to clean furnace off- 
gasses are a potential source of water 
pollution (22) , because scrubber dis- 
charge water generally contains a high 
concentration of suspended solids and or- 
ganic matter (sludge) ( 18) . A sealed 
furnace has been suggested for this oper- 
ation partly because it requires less 
water than an open furnace. Off gas vol- 
umes would be much less; thus, smaller 
scrubbers and a smaller water treatment 
system would be needed. Metals and or- 
ganics in the discharge water may leach 
or percolate from the sludge (23) . All 
water from the scrubbers would be recy- 
cled, and the dewatered sludge would be 
stored in lined disposal ponds. 



25 



The dusts and sludges generated from 
furnaces are primarily particles less 
than a micrometer in size, consisting of 
oxides of Cr, Ca, Mg, and other elements, 
in widely varying proportions depending 
on the product being made. The sludges 
from covered furnaces may also contain, 
in quantities of up to 8 pet, vari- 
ous types of organic compounds. Polycy- 
clic organic matter (POM) content may be 
as high as 65 pet of the organics (5 pet 
of the sludge). Polynuclear aromatic 
hydrocarbons (PNA) , including the known 
carcinogens, benzo(a)pyrene (BaP), 
indeo(l ,2,3-cd)pyrene, and others, may 
occur in significant concentrations. 
Another constituent of sludges may be 
phenol, which is probably derived from 
electrode binding materials in covered 
furnaces (18). 

A leachate test of emission control 
dusts of a ferrochrome furnace, conducted 
by the ferroalloy industry, showed that 
Cr exceeded by 10 times the EPA water 
quality criteria for classification as 
hazardous (20) . Neither the slag nor 
scrubber sludge, also tested, exceeded 
EPA criteria, indicating their stability. 
Although this test was made by the Ferro- 
alloy Association Environmental Commit- 
tee, they feel it is not representative 
of actual dust characteristics. Signifi- 
cant doubt exists as to actual character- 
istics of smelter dust. 

High concentrations of PNA are likely 
in the scrubber water and sludge, and 
previous work indicates that up to 90 pet 
of this type of material can be adsorbed 
on suspended particles. Therefore, it is 
likely that the sludges in the lagoons 
and landfills from covered furnaces con- 
tain high concentrations of PNA, possibly 
exceeding the minimum limits for acute 
toxicity for effluent solid wastes (23). 
The aqueous solubility of PNA's is unaf- 
fected by solution pH, so no chemical pH 
control can be taken. 

Chemical treatment, clarif ier-f loccu- 
lators, sand filters, and recirculation 
would be required to meet the water ef- 
fluent standards for electric ferroalloy 
furnaces when scrubbers are used (22) . 

Waste water purification normally con- 
sists of solids removal by settling in 
unlined ponds or filtration before any 



chemical treatment of the water; thus, 
the solids and the potential organics 
contained within receive essentially no 
treatment. Scrubber sludge is normally 
disposed of in settling ponds. When a 
pond is filled, a new one is constructed 
or the old one is dredged for reuse. The 
Ferroalloy Association estimates 85 pet 
or more of all sludge wastes nationwide 
are disposed of in landfills or lagoons, 
and less than 15 pet are recycled, re- 
claimed, or sold. Industry sources state 
that sludges are essentially self-sealing 
within a pond, so no linear or imperme- 
able soil condition is necessary (18) . 
However, sludge from the potential smelt- 
er would be dewatered and stored in a 
double-lined disposal site. 

A general waste water treatment system 
for ferroalloy production is shown in 
figure 18. The process needed for Cr 
production may not contain all of the 
stages shown, but figure 18 gives an ap- 
propriate general scheme of what might be 
expected in waste water control. The 
diagram is explained by Williams (15): 
The pH is raised to about 11, and 
sufficient chlorine is added to 
maintain a free residual, followed 
by sedimentation. This step oxi- 
dizes phenol and cyanide (to cya- 
nite) and phosphates and manganese 
are precipitated. In the second 
step, additional chlorine is added 
and the pH is lowered to 7.0 by a 
suitable acid. With a reaction 
time of 60 minutes, the cyanate is 
oxidized to CO2 and N2« In the 
third step, the pH is lowered to 
2.5 and sulfur dioxide is added. 
After a reaction time of about 30 
minutes, the hexavalent Cr is re- 
duced to the trivalent state. The 
fourth step consists of raising the 
pH to 8.2, adding a polyelectro- 
lyte and allowing sedimentation. 
At this point, the trivalent chro- 
mium is removed and final clar- 
ification is accomplished. With a 
sufficiently low overflow rate and 
addition of flocculants in suffi- 
cient quantities, a concentration 
of 25 mg/L (milligrams per liter) 
suspended solids can be attained 
and metals can be reduced to low 



26 




Sludge 
disposal 
or metal 
recovery 



0.5-gpm/ft 
rise rate 
at pH 8.2 



FIGURE 18. - Ferrochrome smelter water treatment system. (From Williams (\6). 



levels. Sand filtration of the fi- 
nal clarifier effluent, with back- 
wash returned to the clarifier, 
can reduce suspended solids concen- 
trations to 15 mg/L or less. After 
filtration, the water may be recy- 
cled back to the scrubbers. 
Water needed for the smelting process can 
be acquired from a well, directly from 
the Stillwater River, or from the milling 
process. Because all waste water is to 
be recycled, makeup water would be mini- 
mal (i.e., makeup for evaporation). 

NICKEL-COPPER PROCESSING WASTE WATER 

Detailed data on the characteristics 
of waste water from the Ni-Cu process 
are not available. However, a general 
description of waste water disposal is 
possible. 

Water and reagents used in the bulk 
flotation stage of the process would gen- 
erally be recirculated. However, some 
water and reagents would report to the 



tailings pond with the tailings. Clari- 
fied water would be decanted from the 
tailings pond and reused. Excess water 
would evaporate. 

Waste water from the leach circuit 
would be neutralized with lime and sent 
to the tailings pond where it would ei- 
ther be recycled or evaporate. Sludge 
residue from the leaching circuit would 
be neutralized with lime, slurried, and 
sent to the tailings pond (18) . The zero 
discharge requirements should be attain- 
able in the planned Ni-Cu process. 

DIVERSION OF STREAMS 

Verdigras Creek runs though the middle 
of the Ni-Cu zone and would need to be 
diverted away from the open pit. The 
creek would be diverted about 3,000 ft 
west to Mountain View Lake (fig. 5), 
which would reduce water pollution by 
reducing the amount of water flowing 
through the Ni-Cu pit. 



27 



Water in Verdigras Creek is cur- 
rently of lower quality than water in 
other streams in the area because it 
flows through the Ni-Cu zone. The di- 
version is expected to increase water 
quality in Verdigras Creek by routing 
the creek through less reactive geologic 
formations. 

An unnamed creek shown in figure 7 
would also need to be diverted for the 
high-end PGM scenario, the Ni-Cu scenar- 
io, and the combined operations scenario. 
Diversion reduces the possibility that 
heavy runoff from this creek would enter 
the tailings pond. The creek would be 
diverted to the east around the planned 
dam. 

SUMMARY OF WATER ISSUES 

Baseline studies show that water qual- 
ity in the Stillwater Complex ranges from 
poor to good. Table 3 shows that samples 
occasionally exceeded standards for Cd, 
Cr, Fe, Mn, Pb, fecal bacteria, and tur- 
bidity. Generally, the poorest samples 
were taken during the spring, when flows 



and suspended solids were high. Mine 
drainage water quality was better than 
expected; only one sample exceeded crite- 
ria for Cr. 

New source performance standards for Ni 
and Pt mining and milling call for zero 
discharge of process water, with a few 
exceptions. A performance standard has 
not been set for Cr mining and milling. 
The processes that would be used in the 
Stillwater Complex should be able to 
achieve these standards. 

The characteristics of Cr smelter waste 
water are unclear. Some evidence ex- 
ists suggesting that high concentrations 
of organic compounds may be present in 
sealed-furnace smelters. If so, waste 
water treatment would be needed, and an 
appropriate technique is suggested. Ad- 
ditional research is indicated. 

In summary, existing technology should 
allow any mining operation except ferro- 
chrome smelting to meet water quality 
regulations. Ferrochrome smelting waste 
water has unknown characteristics and may 
pose treatment problems. 



AIR ISSUES 






With the exception of the ferrochrome 
smelter, air quality issues seem to be 
less significant than land or water is- 
sues. In this section, information is 
presented on the baseline air quality and 
emissions from the ferrochrome smelter 
and other sources. 

BASELINE AIR QUALITY 

The climate of the Stillwater Complex 
is mountainous continental. Large varia- 
tions in elevation (from 5,000 to 10,000 
ft) cause large variations in local cli- 
mate and precipitation. Mountain ridges 
and valleys redirect prevailing winds. 
During feasibility studies for potential 
PGM operations, weather and air quality 
sampling stations were established at 
several points in the Stillwater Complex 
(17) . These stations recorded tempera- 
ture, wind speed, wind direction, precip- 
itation, total suspended particulates, 
and other parameters. Data presented 



here are primarily from the Stillwater 
River Valley because it would be the lo- 
cation of the most activity. 

Average temperature in the Stillwater 
River Valley is 45° F. The date of the 
first frost is mid-September, while the 
last frost occurs in mid- June. Annual 
temperature range is about 50° F, winter 
to summer. Temperatures at higher eleva- 
tions are much lower, and freezing tem- 
peratures may occur at any time at eleva- 
tions over 7,500 ft. Timberline in the 
area is at about 9,700 ft. Precipitation 
in the valley ranges between 5 and 60 
in/yr. One-third to one-half of the pre- 
cipitation occurs in April, May, and 
June. The smallest amount of precipita- 
tion occurs in the winter months of No- 
vember through March. Annual precipita- 
tion at the Minneapolis Adit is estimated 
to be about 20 in/yr, while annual pre- 
cipitation at the Hertzler Ranch site is 
estimated to be about 15 in/yr (17). 



28 



Persistent westerly winds blowing down 
the Stillwater River Valley and occa- 
sional southerly chinook winds tend to 
reduce snow accumulations in the valley. 
At higher elevations , an increasing pro- 
portion of precipitation occurs as snow. 
At elevations over 7,500 ft, over 75 pet 
of the precipitation occurs as snow (17) . 

A diurnal wind pattern typical of moun- 
tain valleys exists in the Stillwater 
River Valley. Daytime upslope winds and 
nighttime downslope winds are caused by 
heating from the sun. Prevailing wester- 
ly winds tend to reduce the upslope con- 
dition because they blow down the valley. 
Strong downslope winds are channeled by 
the valley and are common in the winter 
to early spring months. Wind speed and 
direction roses are shown in figure 19. 

Data on the inversion heights in the 
Stillwater River Valley have not been 
complied, but data are available for 



30 pel 




30 pel 



12-4 p.m. 4-8 p.m 8-12 midnight 

DIURNAL WIND DIRECTION ROSES 



similar valleys, and estimates have been 
made based on these data. 

Very strong nighttime temperature in- 
versions are likely to occur, owing to 
intense cooling under clear nighttime 
skies. These inversions are expected to 
be most intense during the winter months. 
Inversion height is estimated to be about 
500 ft above the valley floor (17). Per- 
sistent westerly winds, common in the 
valley, will reduce the frequency and in- 
tensity of these inversions. During the 
winter, winds under 5 mph occur less than 
5 pet of the time. 

When strong temperature inversions ex- 
ist, mixing under the inversion is poor 
and pollutants can become trapped in the 
valley. Poor air quality can result. As 
mentioned above, this condition would 
be most likely to occur during the win- 
ter months on days when strong winds are 
absent. 

Measurements of total suspended partic- 
ulates in the Stillwater River Valley 
averaged between 14 and 20 yg/m 3 . The 
Federal standard is 260 ug/m 3 , and the 
Montana standard is 200 yg/m 3 . All re- 
corded measurements fell well below these 
standards (17) . However, both Federal 
and State clean air regulations use the 
principle of "no significant deteriora- 
tion" of air quality, meaning that per- 
mits granted by these authorities will 
require that emissions not "significant- 
ly" change total suspended particulates 
levels in the valley. Increments of de- 
terioration may be allowed at the discre- 
tion of the permit authority. 




; 20 pel 

,30 pet 



Wind speed class (mph) 
2 7 11 18 25 



WIND SPEED ROSE 

FIGURE 19. - Wind roses from the Stillwater 
River Valley. 



FERROCHROME SMELTER GAS EMISSIONS 

The submerged electric arc furnace 
(fig. 20) is sealed and produces an off- 
gas rich in CO. The offgas is scrubbed 
(particulates removed) by use of a high- 
energy venturi scrubber (wet process). 
Gaseous effluents include mainly CO, fol- 
lowed by volatilized metallics, sulfur 
oxides, cyanides, phenols, and oil, and 
are usually treated by combustion (22) . 
Normally, the CO-rich gas is flared, but 
here in order to decrease pollution and 
increase energy efficiency, it is pro- 
posed to be used as fuel to dry mill con- 
centrates. The effectiveness of flares 



29 



Electrodes 
/ \ 



Bag house 




Water Water 

FIGURE 20. - Ferrochrome smelter air control system. 



. Option of 
' flaring gas 



Co-rich gas 

for fuel 

to dryer 



scrubber control 
for the proposed 



or burning in general for destroying 
higher molecular weight organic matter is 
questionable, since test data show that 
organics survive even in gases from open 
furnaces, which burn vigorously. 

The general trend for submerged arc 
ferroalloy production facilities is to 
use an open-type furnace with a, baghouse 
to remove particulates from the gas 
stream. About 70 pet of all submerged 
arc ferroalloy furnaces in the United 
States in May 1980 were open furnaces 
with baghouses (22). However, a sealed 
furnace with venturi 
equipment was chosen 
chromite refining. CO gas can be recov- 
ered from this type of furnace, and 
smaller scale pollution control devices 
are utilized because smaller volumes of 
gas are produced by the furnace. All 
covered furnaces in the United States use 
scrubbers as control equipment rather 
than baghouses. Gas from sealed furnaces 
contains fumes, particulates, high con- 
centrations of CO, some CO2 and H 2 , and 
several types of organic matter. The 
high CO content of the offgas makes it 
potentially explosive and hazardous to 
breathe. A baghouse for collection of 
offgas particulates would be hazardous 
because of the high CO content and the 
toxic and volatile nature of the gas. A 
typical ferrochrome smelter air control 
system is shown in figure 20. 

The EPA reports that sealed furnaces 
have much lower gas emission rates than 
open furnaces (22) . The power require- 
ments for their control systems are usu- 
ally much lower than those for open 



furnaces. Open furnace control equipment 
must handle gas volumes typically 50 
times greater than the volumes from 
sealed furnaces. Even 20 to 35 pet of 
the energy supplied to a closed furnace 
can be recovered by fueling processing 
equipment such as dryers, pellet fur- 
naces, and sintering machines with C0- 
rich gas from the furnace. Only about 2 
pet of the power used in operating sealed 
furnaces is needed for pollution control. 

The control systems should be well 
sealed and the work areas ventilated. 
Mechanical seals are used around the 
electrodes on a sealed furnace, and the 
feed mix is added through sealed chutes 
(22). No gas or fume is allowed to es- 
cape from the furnace cover, and only 
a minimal secondary hood airflow is re- 
quired. There is no air leakage into the 
furnace, so combustion is prevented. Two 
advantages of the sealed furnace are 
reduced escape of gas and fumes from 
the furnace cover and a lower cover 
temperature. 

About 173 and 411 tpd of gases are at- 
tributable to smelting for the low- and 
high-end scenarios, respectively. Com- 
puter modeling would be required to esti- 
mate the impact such emissions would have 
on air quality, but some major character- 
istics can be identified. The relatively 
high volume of gases could significantly 
affect air quality in the Stillwater 
River Valley on occasions. The prevail- 
ing westerly winds may tend to clear the 
valley most of the time, but possible 
strong temperature inversions on calm 
winter mornings may trap pollutants in 



30 



the valley. On days when strong inver- 
sions are present, CO and particulates 
from the smelter combined with CO and 
particulates from automobiles and fire- 
places could lower air quality. 

Tapping fumes would be controlled by a 
hood and fan sending gaseous effluents to 
a baghouse or another scrubber. When the 
furnace is tapped, fumes occur as a re- 
sult of (1) burning the C plug out of the 
taphole, (2) oxidation of hot metal, and 
(3) vaporization of organics in the C 
used as a lip liner when opening or seal- 
ing the taphole. Emissions when tapping 
are of short duration and are partially 
captured by the taphole emission control 
system. Fumes not captured are vented 
and dispersed through the building's roof 
monitors. Although the fumes could con- 
tain hazardous organic compounds, their 
concentrations are rapidly reduced by 
dilution with air. Most plants have sys- 
tems that capture the particulates in a 
baghouse. Most other fumes and dust oc- 
cur as metallic components similar to the 
alloy during transfer, cooling, grinding, 
and packing of the alloy. All water from 
the scrubbers would be recycled. 

DUST 

Several potential sources of dust 
exist, but detailed data to quantify 
amounts do not. A general description of 
these potential sources follows. 

During the lifetimes of the PGM, Ni-Cu, 
and chromite projects, periods will oc- 
cur when portions of the tailings ponds 
are dry and are potential sources of fu- 
gitive dust. Such areas cannot be reveg- 
etated until they are dry enough to sup- 
port mechanical equipment, but chemical 
dust suppressants could be used to effec- 
tively minimize the problem. Chemical 
composition of the tailings should not 
pose any health risks as they are not 
known to contain asbestiform minerals or 
other irritants. Chromium in the tail- 
ings would be in the less hazardous tri- 
valent state and would be present in low 
concentrations . 



The Ni-Cu open pit is another poten- 
tial source of dust. Haul roads in the 
mine, blasting, and crushing are poten- 
tial sources of dust. Most of these 
sources can be effectively controlled, 
however. Haul roads can be periodically 
watered, blasting can be designed to min- 
imize fines production, and dust from the 
crusher would be contained in a baghouse, 
as required by current regulations. It 
is impossible to quantify the amount of 
dust generated by the various operations, 
but existing technology is generally ef- 
fective in controlling emissions from 
these types of sources. 

OTHER AIR ISSUES 

The most significant air issue not al- 
ready addressed is the possibility of 
residential air pollution caused by auto- 
mobiles, wood-burning stoves, and fire- 
places. As previously mentioned, strong 
air temperature inversions are possible 
in the valley during the winter months. 
A large proportion of the expanded pop- 
ulation of the area would be expected 
to use stoves and fireplaces. Smoke and 
CO from stoves and fireplaces could be 
trapped in the valley by the inversion, 
resulting in poor air quality. Catalytic 
converters could be installed on pri- 
vate wood-burning stoves to alleviate the 
problem but would probably have to be 
required by local ordinance. 

The persistent prevailing westerly 
winds during the winter months will tend 
to reduce the occurrence of this condi- 
tion. Less than 5 pet of winter mornings 
would be susceptible to inversion-caused 
pollution. 

Mine ventilation air may contain sus- 
pended particulates. This air exhaust 
would contain respirable dust, nitrous 
fumes from blasting, and diesel vehicle 
exhaust. Amounts should be relatively 
low and are not expected to impact air 
quality. 



OTHER ISSUES 



31 






NOISE 

Potential sources of frequent noise 
would be haulage trucks and blasting in 
the Ni-Cu open pit, as well as main 
ventilation fans for the underground 
mines; some noise would also be associ- 
ated with the ferrochrome smelter. In- 
frequent noise would come from trains 
bringing in supplies and transporting 
products to market. 

POWER, TRANSPORTATION, AND HOUSING 

Twin transmission lines could be con- 
structed between Columbus and the ferro- 
chrome smelter, 45 MW for the low-end 
scenario and 110 MW for the high-end sce- 
nario. The present 50 kW transmission 
line is insufficient to meet the needs of 
any potential operation. This line would 
have to be upgraded in order to support 
the increase in population resulting from 
mining. The PGM and Ni-Cu mining would 
need substantially less power than the 
chromite mine-mill-smelter complex. 

The road between Columbus and the mine- 
mill sites would probably have to be up- 
graded to accommodate the increased traf- 
fic load resulting from mining. Heavy 
equipment would probably be brought in by 
rail, thus reducing the amount of road 
upgrading. 

A spur rail line from Columbus to the 
mill area would be necessary for the Cr 
mine-mill-smelter complex. Trains could 
better handle the large volume of flux, 
coal, and other material needed for pro- 
ducing ferrochrome, and could transport 
the ferrochrome to a main rail line. The 
spur line could also be used to bring in 
mine, mill, and smelter equipment. 



Most people employed by these potential 
operations would reside in Stillwater 
County, which had a population of 5,597 
in 1980. Chromium operations would em- 
ploy 90 to 200 people, PGM operations 
would employ 170 to 520 people, and Ni-Cu 
operations would employ 150 to 300 peo- 
ple. Assuming an average of two depen- 
dents for each employee, the population 
increase would be 220 to 600 people for 
Cr operations, 510 to 1,560 people for 
PGM operations, and 450 to 900 people for 
Ni-Cu operations. The percentage popu- 
lation increases for Stillwater County 
would be 5 to 11 pet for Cr operations, 9 
to 30 pet for PGM operations and 8 to 16 
pet for Ni-Cu operations. Combined oper- 
ations would result in a 22- to 57-pct 
increase in the population of Stillwater 
County. 

The towns of Nye, Fishtail, Absaroka, 
and Columbus would experience growth due 
to these operations. Nye and Fishtail 
(both unincorporated) are nearest to the 
operations and are the smallest of the 
communities. Housing constructed in 
these communities would include single- 
family homes, trailers, and apartments. 
The school of Nye may have to be ex- 
panded. Police and fire protection in 
the upper part of the valley may have to 
be increased. 

Sufficient lead time would be required 
for local officials to plan for orderly 
growth if mining operations become real- 
ity. Once detailed mine plans have been 
formulated, local officials can prepare 
plans for roads, schools, fire protec- 
tion, and police services. Costs can be 
estimated and suitable taxes and bonds 
instituted. This process could take over 
2 yr to complete. 



CONCLUSIONS 



In this report, the environmental is- 
sues of potential development of strate- 
gic and critical minerals in the Stillwa- 
ter Complex were discussed. Specific 
land, water, air, and other environmental 



issues were identified and analyzed as to 
how they would relate to mining of Cr, 
PGM, and Ni-Cu deposits located in the 
Stillwater Complex. 



32 



Chromium would be mined underground 
using shrinkage stoping methods. Mill- 
ing would be by gravity concentration. 
Smelting would be done on-site using a 
sealed furnace. Mill feedrate would 
range from 1,000 to 2,500 tpd ore. 

PGM would be mined underground using 
shrinkage stoping or cut-and-fill stoping 
methods. Milling would be by froth flo- 
tation using a low-pH method. Concen- 
trate would be refined elsewhere. Mill 
feedrate ranges from 1,000 to 4,000 tpd 
ore. 

Nickel-copper ore would be mined using 
open-pit methods. Milling would be by 
froth flotation and Cl-0 2 leach. Refin- 
ing would be by electrolysis and precipi- 
tation. Mill feedrate would be about 
27,500 tpd ore. 

The most significant environmental 
isssues center around the ferrochrome 
plant. This plant would produce a sludge 
high in organic content. The plant would 



be highly visible and require significant 
amounts of electric power. 

The Ni-Cu open pit and dump would be 
visible during active mining. The tail- 
ings pond resulting from the operation 
would require an area of over 600 acres . 

PGM mining would also be highly visible 
during active mining. The area required 
for tailings disposal ranges from 75 to 
300 acres depending on size and mining 
method. 

Technology for reclamation and minimi- 
zation of environmental effects seems to 
be well defined, with the exception of 
sludge disposal for the ferrochrome 
smelter. Zero net waste water discharge 
should be achievable for all operations. 
Reclamation technology for all solid 
waste (except ferrochrome smelter sludge) 
is available and sound. Visual impact 
and land use changes are unavoidable 
effects. 



REFERENCES 



1. U.S. Bureau of Mines. Mineral Com- 
modity Summaries 1984, 185 pp. 

2. Hargreaves , D. , and S. Fromsen. 
World Index of Strategic Minerals: 
Production, Exploitation, and Risk. 
Facts on File, Inc., New York, NY, 1983, 
299 pp. 

3. Jolly, J. H. Platinum-Group Met- 
als. Ch. in Mineral Facts and Prob- 
lems, 1980 Edition. BuMines B 671, 1981, 
pp. 683-706. 

4. Golden, J., R. P. Ouellette, S. Sa- 
ari, and P. N. Cheremisinof f . Environ- 
mental Impact Data Book. Ann Arbor Sci., 
1979, 864 pp. 

5. Price, P. M. Mining Methods and 
Costs, Mouat Mine, American Chrome Co., 
Stillwater County, Mont. BuMines IC 
8204, 1963, 58 pp. 

6. Sullivan, G. V., and G. F. Worken- 
tine. Benef iciating Low-Grade Chromites 
From the Stillwater Complex, Montana. 
BuMines RI 6448, 1964, 28 pp. 

7. Page, N. J., and W. J. Nokleberg. 
Geologic Map of the Stillwater Complex, 
Montana. U.S. Geol. Surv. Misc. Invest. 
Series Map 1-797, 1974, 5 plates. 



8. Bow, C. , C. Wolfgram, A. Turner, 
S. Barnes, J. Evans, M. Zdepski, and 
A. Boudreau. Investigations of the How- 
land Reef of the Stillwater Complex, Min- 
neapolis Adit Area: Stratigraphy, Struc- 
ture, and Mineralization. Econ. Geol., 
v. 77, 1982, pp. 1481-1492. 

9. Perlmutter, S. J. Montana Envi- 
ronmental Permit Directory. MT Environ. 
Qual. Counc, 1982, 27 pp. 

10. Montana Department of State Lands 
and U.S. Forest Service. Draft Environ- 
mental Impact Statement, Stillwater Min- 
ing Co. Stillwater Project, Stillwater 
County. 1985, 259 pp.; available from MT 
Dep. State Lands, Helena, MT. 

11. Federal Register. U.S. Environ- 
mental Protection Agency. Ore Mining and 
Dressing Point Source Category Effluent 
Guidelines and New Source Performance 
Standards. V. 47, No. 233, Dec. 3, 1982, 
pp. 54597-54621. 

12. Yamada, K. Stainless Steelmaking 
by the LD-AOD Process. Ch. in Iron and 
Steelmaker. Iron and Steel Soc. AIME, 
1982, pp. 29-33. 



33 



13. Morrice, E. Pilot Mill Flotation 
of Anorthositic Platinum-Palladium Ore 
From the Stillwater Complex. BuMines 
RI 8763, 1983, 8 pp. 

14. Baglin, E. G. , J. M. Gomes, and 
M. M. Wong. Recovery of Platinum-Group 
Metals From Stillwater Complex, Mont., 
Flotation Concentrates by Matte Smelt- 
ing and Leaching. BuMines RI 8717, 1982, 
15 pp. 

15. Williams, R. E. Waste Production 
and Disposal in Mining, Milling, and Met- 
allurgical Industries. Miller Freeman, 
San Francisco, CA, 1975, 489 pp. 

16. Smyres, G. A. Chlorine-Oxygen 
Leaching of Complex Sulfide Concentrates. 
AIME preprint A7786, 1977, 9 pp. 

17. The Anaconda Company. Operating 
Permit Application for a Platinum/Palla- 
dium Mine, Stillwater County, Montana. 
Unpublished report, 1981, 3 v., 600 pp.; 
available from MT Dep. State Lands, 
Reclam. Div. , Helena, MT. 

18. Westbrook, W. Ferroalloy Fur- 
naces: Generation and Emission of Par- 
ticulate and Organic Matter. Paper in 



39th Electric Furnace Conference Proceed- 
ings. Iron and Steel Soc. AIME, 1981, 
pp. 226-242. 

19. Beak Consultants, Ltd. Surface 
Water Resources for the Stillwater PGM 
Resources Project. Unpublished report, 
Tech. Rep. 4, 1982, pp. 41-48; available 
from MT Dep. State Lands, Reclam. Div., 
Helena, MT. 

20. U.S. Environmental Protection 
Agency. Quality Criteria for Water. 
1976, 260 pp. 

21. National Research Council. Medi- 
cal and Biological Effects of Environmen- 
tal Pollutants: Chromium. Natl. Acad. 
Sci., Washington, DC, 1974, 155 pp. 

22. U.S. Environmental Protection 
Agency. Background Information for Stan- 
dards of Performance: Electric Submerged 
Arc Furnaces for Production of Ferroal- 
loys. Volume I: Proposed Standards. 
EPA-450/2-74-018a, 1974, 174 pp. 

23. . Level 1 Environmental As- 
sessment of Electric Submerged-Arc Fur- 
naces Producing Ferroalloys. EPA-600/2- 
82-083, 1981, 333 pp. 



■frU.S. CPO: 1985-505-019/20,091 



INT.-BU.OF MINES,PGH.,PA. 28080 



33 



jP<*. 



V"^ 






*v^v v : ^*>' V^y .. \>^*\/ v^>° .. ^' 



»-> ^ c^ .vatef. ^ ** .W/k'. *«« .<£*' .*■ 



^ A^^ 














*<u** .vS&te \^* .\flK-, W 














b. .4* ..••••« ^6 ,0* c»"«* 










^0* 







A^^ 



^ yj^^\ 



<. '<,.»» .& 






•b V" . 




• %*> 4 * 




V^v* %^ f, V° v*^v "V 



• V -Mfe w -III- %/ «& ^* «* %/ #|& w 



V G* *o '^? 



A^* 



*° ♦♦"*♦ 














» * 






k *^ ^ 



^Qf 



^ 













v n o 



'bv* 








$> *o«o° 



-"'/^ G°Vi&L>>o ./^^A. > /^^°- J*\£&>-%. C°* 



V ^751^'^ ^ rt ^ o^<^0i-. ^ oV V ;7J^ ^ <- .^^IK- ^b^ :^&'^ ^o* •■ 






jp^h 



^°* 



^■^ 



v ^°- 



v-^-\/ v-^^*/ V^->" \-»V' v*^-/ %*=^' 










: ' X^^-3K\' V^\.-S^:X^';aK: ' V*';SC& \f 






,'- S 




y o>° 



jp-n*. - 

r >' .0° % * 




^' / V 









v b.. *'T7T' ' .A <, - '^. 7 - A G- ^ *.^T^ a A 



r- **d* • 










-^. - . , -i • ' A." "<J> * o « o ' «,v ^ *.,•>• A,' 

•o V A^ . V ^fe'. ^ a^ /rf^^A" ^n <£ • ' 



» " ° ♦ -O 




./>/' 



"oV" 



s^ A 



4, v ^f> 










«*P^ "^ 
%. '" ^ , . • . *>. " » • 




<?, * o » o ' ^) V 



-V ^ • 



+* .li^% ** 






'bv' 
*P^. y 



^ < 



• t^sVW.*.^. O 



>' .o v 'o -<Trr'' a <» 'o^. 1 ;' ,g v ^ *^rr*' a <» '».^« ^g 



./.•^•:\ 



'by' 




%^^-/ °v^y v*^\/ %^ % \* %>^\<? %^ > 









•bV" 



•_• ^ c%, -yaw*'** J) 'j. *y 



?.' *> 



"^ ^ 

^°^ 



i-. %.^ /Jte'^ %/ .*^T. \/ :«•- %/ .'^fi&: \/ «»: %/ 

<» '» . » * aG V 







>^, * ° » « ' .« 



• ** .*♦ .^VA-» ^ >* /iSftJ\ V.** :^4; V^ 



[: %&* •* 






if 1 "3 



*i/nL'* *> 



rt * 



-Of 














*bV 







o, *' . .T« A 














*bV^ 






G* *o *^*V A V 






°q, *^'V 




^(F 







i o 



^ V 



•bv" 




• W .38£ V* 7&fe: \/ ••« \^ .•&&• \/ • 






* 0> 



•' **% •• 



£*» 



iV^ 






^..—- ^ .0* ..*•♦ ^o '••■>'.....,%. "* ^' 



>:\. 






o 41 


















> ^"'••'•* A 6 * ^.*^^\< V * *</'-£.**.&** < V' - ^^**A* t>* 







.6* ^b 





A>"^ 













■* -^8K* ** ^ ffW / ^ v. 

"o *^T* A <* '».»" .G v \s *^T 4 A 



>b& 




& B » 






V * v %«< 
















A^"V 




»«<>' f 



V v ' ° °* 










V^" /JS»\ ' V,**' 'Wm "tfc. **- , i . 









»P^ 



<\. 'o . * * .G 



*• .^ "^ '.^P, 4 . ** * 






^o *.T.V A 

bv* 







• ^ A* V *' 

» o 









•^ \-^/ ^/«l^.^ ^ 








A ^ V "V 

y \?» °y 



<> *o . » ' 












*bV" 




^6* 



• -or o 




o. *^t;%* a 
. "*b A* ." 



<, 




V ; "^'*^ °^ 4 ^ f '%o° \ J ^'\4T %*7Wj? 



LIUKAKVOFCONGR 



002 955 962 4 



i ..' 












■ 






